EP2693134A1 - Air conditioning apparatus - Google Patents
Air conditioning apparatus Download PDFInfo
- Publication number
- EP2693134A1 EP2693134A1 EP12763704.9A EP12763704A EP2693134A1 EP 2693134 A1 EP2693134 A1 EP 2693134A1 EP 12763704 A EP12763704 A EP 12763704A EP 2693134 A1 EP2693134 A1 EP 2693134A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- side refrigerant
- primary
- refrigerant
- heat exchanger
- flow
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 238000004378 air conditioning Methods 0.000 title claims abstract description 114
- 239000003507 refrigerant Substances 0.000 claims abstract description 942
- 239000007788 liquid Substances 0.000 claims abstract description 72
- 238000010438 heat treatment Methods 0.000 claims description 82
- 238000001816 cooling Methods 0.000 claims description 80
- 230000007246 mechanism Effects 0.000 claims description 43
- 230000000694 effects Effects 0.000 claims description 14
- 239000000203 mixture Substances 0.000 claims description 14
- 230000008859 change Effects 0.000 claims description 13
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 13
- 239000012267 brine Substances 0.000 claims description 7
- HPALAKNZSZLMCH-UHFFFAOYSA-M sodium;chloride;hydrate Chemical group O.[Na+].[Cl-] HPALAKNZSZLMCH-UHFFFAOYSA-M 0.000 claims description 7
- 239000000654 additive Substances 0.000 claims description 3
- 230000000996 additive effect Effects 0.000 claims description 3
- 238000005260 corrosion Methods 0.000 claims description 3
- 238000010586 diagram Methods 0.000 description 28
- 230000009471 action Effects 0.000 description 12
- 238000000034 method Methods 0.000 description 8
- 230000008569 process Effects 0.000 description 8
- 238000010521 absorption reaction Methods 0.000 description 6
- 230000009467 reduction Effects 0.000 description 5
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 4
- ATUOYWHBWRKTHZ-UHFFFAOYSA-N Propane Chemical compound CCC ATUOYWHBWRKTHZ-UHFFFAOYSA-N 0.000 description 4
- 230000005855 radiation Effects 0.000 description 4
- 239000007787 solid Substances 0.000 description 4
- 238000009434 installation Methods 0.000 description 3
- 239000004215 Carbon black (E152) Substances 0.000 description 2
- 229910052799 carbon Inorganic materials 0.000 description 2
- 229910002092 carbon dioxide Inorganic materials 0.000 description 2
- 239000001569 carbon dioxide Substances 0.000 description 2
- NBVXSUQYWXRMNV-UHFFFAOYSA-N fluoromethane Chemical compound FC NBVXSUQYWXRMNV-UHFFFAOYSA-N 0.000 description 2
- 229930195733 hydrocarbon Natural products 0.000 description 2
- 150000002430 hydrocarbons Chemical class 0.000 description 2
- 238000005457 optimization Methods 0.000 description 2
- 239000001294 propane Substances 0.000 description 2
- 230000006872 improvement Effects 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
Images
Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B13/00—Compression machines, plants or systems, with reversible cycle
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B2309/00—Gas cycle refrigeration machines
- F25B2309/06—Compression machines, plants or systems characterised by the refrigerant being carbon dioxide
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B2313/00—Compression machines, plants or systems with reversible cycle not otherwise provided for
- F25B2313/003—Indoor unit with water as a heat sink or heat source
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B2313/00—Compression machines, plants or systems with reversible cycle not otherwise provided for
- F25B2313/006—Compression machines, plants or systems with reversible cycle not otherwise provided for two pipes connecting the outdoor side to the indoor side with multiple indoor units
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B2313/00—Compression machines, plants or systems with reversible cycle not otherwise provided for
- F25B2313/023—Compression machines, plants or systems with reversible cycle not otherwise provided for using multiple indoor units
- F25B2313/0231—Compression machines, plants or systems with reversible cycle not otherwise provided for using multiple indoor units with simultaneous cooling and heating
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B2313/00—Compression machines, plants or systems with reversible cycle not otherwise provided for
- F25B2313/023—Compression machines, plants or systems with reversible cycle not otherwise provided for using multiple indoor units
- F25B2313/0233—Compression machines, plants or systems with reversible cycle not otherwise provided for using multiple indoor units in parallel arrangements
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B2313/00—Compression machines, plants or systems with reversible cycle not otherwise provided for
- F25B2313/027—Compression machines, plants or systems with reversible cycle not otherwise provided for characterised by the reversing means
- F25B2313/0272—Compression machines, plants or systems with reversible cycle not otherwise provided for characterised by the reversing means using bridge circuits of one-way valves
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B2400/00—General features or devices for refrigeration machines, plants or systems, combined heating and refrigeration systems or heat-pump systems, i.e. not limited to a particular subgroup of F25B
- F25B2400/12—Inflammable refrigerants
- F25B2400/121—Inflammable refrigerants using R1234
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B9/00—Compression machines, plants or systems, in which the refrigerant is air or other gas of low boiling point
- F25B9/002—Compression machines, plants or systems, in which the refrigerant is air or other gas of low boiling point characterised by the refrigerant
- F25B9/008—Compression machines, plants or systems, in which the refrigerant is air or other gas of low boiling point characterised by the refrigerant the refrigerant being carbon dioxide
Definitions
- the present invention relates to an air-conditioning apparatus that has two refrigerant circuits including a primary-side refrigerant circuit and a secondary-side refrigerant circuit, and causes heat to be exchanged between a primary-side refrigerant and a secondary-side refrigerant in an intermediate heat exchanger.
- an air-conditioning apparatus capable of simultaneous cooling and the heating operation which "includes a heat source-side refrigerant circuit A having a compressor 11, an outdoor heat exchanger 13, a first refrigerant branch part 21 connected to the compressor 11, a second refrigerant branch part 22 and a third refrigerant branch part 23 connected to the outdoor heat exchanger 13, a first refrigerant flow control device 24 provided between a branch pipe 40 and the second refrigerant branch part 22, intermediate heat exchangers 25n whose one side is connected to the first refrigerant branch part 21 and the third refrigerant branch part 23 via three-way valves 26n and whose other side is connected to the second refrigerant branch part 22, and second refrigerant flow control devices 27n provided between each of the intermediate heat exchangers 25n and the second refrigerant branch part 22, and a use-side refrigerant circuit Bn having indoor heat exchangers 31n connected to the intermediate heat exchangers 25n, and in which
- Patent Literature 1 WO2009/133640 A (Abstract)
- Patent Literature 1 has the following problem. That is, while the direction of the heat source-side refrigerant flowing through the intermediate heat exchangers changes depending on the operation mode, the flow of the use-side refrigerant is a certain direction. Therefore, appropriate heat exchange efficiency is not obtained in intermediate heat exchangers in which these refrigerants are in parallel flow, which makes it impossible to perform optimum operation in all operation modes.
- the present invention has been made in view of the problem mentioned above, and accordingly it is an object of the present invention to provide an air-conditioning apparatus which ensures high heat exchange efficiency even when the direction of a heat source-side refrigerant (primary-side refrigerant) flowing through an intermediate heat exchanger changes, and enables an appropriate operation in any operation mode.
- An air-conditioning apparatus includes a primary-side refrigerant circuit in which a compressor, first flow switching means, a heat source-side heat exchanger, second flow switching means, a plurality of intermediate heat exchangers, and an expansion mechanism are connected by refrigerant pipes, and through which a primary-side refrigerant flows, and a secondary-side refrigerant circuit in which the intermediate heat exchangers, third flow switching means, a pump, fourth flow switching means, and a plurality of use-side heat exchangers are connected by refrigerant pipes, and through which a secondary-side refrigerant different from the primary-side refrigerant flows.
- the first flow switching means switches a refrigerant flow path so that the primary-side refrigerant discharged from the compressor flows to each of the intermediate heat exchangers or the heat source-side heat exchanger.
- the second flow switching means switches a flow direction of the primary-side refrigerant flowing into each of the intermediate heat exchangers.
- the third flow switching means switches a flow direction of the secondary-side refrigerant flowing into each of the intermediate heat exchangers.
- the fourth flow switching means switches a refrigerant flow path to direct one of flows of the secondary-side refrigerant that have flown through the plurality of the intermediate heat exchangers to flow through the corresponding each use-side heat exchanger, so that one of a cooling operation and a heating operation is performed in a selectable manner by each of the use-side heat exchangers.
- the second flow switching means and the third flow switching means each switch a refrigerant flow path so that the primary-side refrigerant and the secondary-side refrigerant are in counterflow in at least one of the intermediate heat exchangers.
- the primary-side refrigerant and the secondary-side refrigerant are in counterflow in at least one intermediate heat exchanger. Therefore, thermal effect of the primary-side refrigerant and the secondary-side refrigerant is exerted efficiently, thereby making it possible to reduce the input to the pump.
- FIG. 1 is a schematic diagram of an air-conditioning apparatus according to Embodiment 1 of the present invention, illustrating the flow of a refrigerant in the cooling operation.
- FIG. 2 is a schematic diagram of the air-conditioning apparatus, illustrating the flow of refrigerant in the heating operation.
- arrows indicated by thick lines indicate the flow of a primary-side refrigerant
- arrows indicated by narrow lines indicate the flow of a secondary-side refrigerant.
- the air-conditioning apparatus includes two refrigerant circuits, a primary-side refrigerant circuit, and a secondary-side refrigerant circuit.
- a fluorocarbon refrigerant such as R410A
- a hydrocarbon refrigerant such as propane
- a natural refrigerant such as carbon dioxide
- an azeotropic refrigerant mixture such as R410A
- a zeotropic refrigerant mixture such as R407C, R32, and R134a, or R32 and R1234yf.
- the secondary-side refrigerant that flows through the secondary-side refrigerant circuit for example, brine, water, a liquid mixture of brine and water, a liquid mixture of water and an additive having an anti-corrosion effect, or the like is used.
- the primary-side refrigerant circuit includes at least a compressor 3, an outdoor heat exchanger 4, an expansion mechanism 5, a four-way valve 6, and an intermediate heat exchanger 7.
- the primary-side refrigerant circuit is configured by connecting the compressor 3, the four-way valve 6, the outdoor heat exchanger 4, the expansion mechanism 5, the intermediate heat exchanger 7, the four-way valve 6, and the compressor 3 in this order by refrigerant pipes.
- the secondary-side refrigerant circuit includes at least the intermediate heat exchanger 7, an indoor heat exchanger 8, a pump 9, and valves 10a to 10d.
- the secondary-side refrigerant circuit is configured by connecting the pump 9, the indoor heat exchanger 8, the valve 10b, the intermediate heat exchanger 7, the valve 10a, and the pump 9 in this order by refrigerant pipes.
- a branch part 30a on the refrigerant pipe connecting the indoor heat exchanger 8 and the valve 10b is connected to a branch part 30b on the refrigerant pipe connecting the valve 10a and the intermediate heat exchanger 7, by a refrigerant pipe via the valve 10d.
- a branch part 30c on the refrigerant pipe connecting the intermediate heat exchanger 7 and the valve 10b is connected to a branch part 30d on the refrigerant pipe connecting the pump 9 and the valve 10a, by a refrigerant pipe via the valve 10c.
- the intermediate heat exchanger 7 includes at least heat transfer units 7a and 7b, check valves 11a to 11c, and check valves 12a to 12c.
- each of the heat transfer units 7a and 7b exchanges heat between the primary-side refrigerant and the secondary-side refrigerant, and includes a refrigerant flow path through which the primary-side refrigerant flows and a refrigerant flow path through which the secondary-side refrigerant flows.
- one refrigerant outlet/inlet of the refrigerant flow path through which the primary-side refrigerant flows is connected to the four-way valve 6 by a refrigerant pipe.
- the other refrigerant outlet/inlet is connected to the expansion mechanism 5 by a refrigerant pipe via the check valve 11b.
- one refrigerant outlet/inlet of the refrigerant flow path through which the primary-side refrigerant flows is connected to a branch part 20b on the refrigerant pipe connecting the heat transfer unit 7b and the check valve 11b, by a refrigerant pipe.
- the other refrigerant outlet/inlet is connected to a branch part 20d on the refrigerant pipe connecting the heat transfer unit 7b and the four-way valve 6, by a refrigerant pipe via the check valve 11a.
- a branch part 20c on the refrigerant pipe connecting the heat transfer unit 7a and the check valve 11a is connected to a branch part 20a on the refrigerant pipe connecting the expansion mechanism 5 and the check valve 11b, by a refrigerant pipe via the check valve 11c.
- one refrigerant outlet/inlet of the refrigerant flow path through which the secondary-side refrigerant flows is connected to the valve 10a by a refrigerant pipe.
- the other refrigerant outlet/inlet is connected to the valve 10b by a refrigerant pipe via the check valve 12b.
- one refrigerant outlet/inlet of the refrigerant flow path through which the secondary-side refrigerant flows is connected to a branch part 31 c on the refrigerant pipe connecting the heat transfer unit 7b and the check valve 12b, by a refrigerant pipe.
- the other refrigerant outlet/inlet is connected to a branch part 31a on the refrigerant pipe connecting the heat transfer unit 7b and the valve 10a, by a refrigerant pipe via the check valve 12a.
- a branch part 31d on the refrigerant pipe connecting the check valve 12b and the valve 10b is connected to a branch part 31 b on the refrigerant pipe connecting the heat transfer unit 7a and the check valve 12a, by a refrigerant pipe via the check valve 12c.
- the compressor 3 sucks the primary-side refrigerant in a gas state, compresses the primary-side refrigerant into a high-temperature, high-pressure state, and discharges the resulting primary-side refrigerant.
- the compressor 3 may be configured by, for example, an inverter compressor or the like whose capacity can be controlled.
- the outdoor heat exchanger 4 functions as a radiator in the cooling operation, and functions as an evaporator in the heating operation.
- the outdoor heat exchanger 4 exchanges heat between the outdoor air supplied from a fan 4a and the primary-side refrigerant.
- the expansion mechanism 5 expands and reduces the pressure of the primary-side refrigerant that has flowed out of the outdoor heat exchanger 4 in the cooling operation, and the primary-side refrigerant that has flowed out of the intermediate heat exchanger 7 in the heating operation.
- the four-way valve 6 has the function of switching the refrigerant flow path. Specifcally, in the cooling operation, the four-way valve 6 switches the refrigerant flow path so that the primary-side refrigerant discharged from the compressor 3 flows to the outdoor heat exchanger 4, and that the primary-side refrigerant that has flowed out of the intermediate heat exchanger 7 flows to the compressor 3. In the heating operation, the four-way valve 6 switches the refrigerant flow path so that the primary-side refrigerant discharged from the compressor 3 flows to the intermediate heat exchanger 7, and that the primary-side refrigerant that has flowed out of the outdoor heat exchanger 4 flows to the compressor 3.
- the heat transfer units 7a and 7b are each configured by, for example, a double-pipe heat exchanger, a plate heat exchanger, a micro-channel water heat exchanger, or the like. As described above, each of the heat transfer units 7a and 7b includes a refrigerant flow path through which the primary-side refrigerant flows, and a refrigerant flow path through which the secondary-side refrigerant flows, and exchanges heat between the primary-side refrigerant and the secondary-side refrigerant.
- each of the heat transfer units 7a and 7b causes the primary-side refrigerant to be heated by the secondary-side refrigerant in the cooling operation, and causes the primary-side refrigerant to be cooled by the secondary-side refrigerant in the heating operation.
- each of the heat transfer units 7a and 7b is preferably installed in such an orientation that the primary-side refrigerant flows into each of the heat transfer units 7a and 7b from the lower side when the primary-side refrigerant absorbs heat, and that the primary-side refrigerant flows into each of the heat transfer units 7a and 7b from the upper side when the primary-side refrigerant radiates heat.
- the indoor heat exchanger 8 functions as a cooler in the cooling operation, and functions as a radiator in the heating operation.
- the indoor heat exchanger 8 exchanges heat between the indoor air supplied from a fan 8a and the secondary-side refrigerant.
- the pump 9 causes the secondary-side refrigerant to circuit within the secondary-side refrigerant circuit as the pump 9 is driven.
- the valves 10a to 10d are opening and closing valves, which conduct the secondary-side refrigerant when open, and shut off the flow of the secondary-side refrigerant when closed. Specifically, the valves 10a to 10d have the function of switching the outlet/inlet through which the secondary-side refrigerant that has flowed out of the indoor heat exchanger 8 flows into the intermediate heat exchanger 7.
- the check valves 11a to 11c cause the primary-side refrigerant to flow in only one direction. Specifically, the check valve 11a causes the primary-side refrigerant to flow only in a direction from the branch part 20c toward the branch part 20d. The check valve 11b causes the primary-side refrigerant to flow only in a direction from the branch part 20a toward the branch part 20b. The check valve 11c causes the primary-side refrigerant to flow only in a direction from the branch part 20c toward the branch part 20a.
- the check valves 12a to 12c cause the secondary-side refrigerant to flow in only one direction. Specifically, the check valve 12a causes the secondary-side refrigerant to flow only in a direction from the branch part 31 a toward the branch part 31b. The check valve 12b causes the secondary-side refrigerant to flow only in a direction from the branch part 31 c toward the branch part 31d. The check valve 12c causes the secondary-side refrigerant to flow only in a direction from the branch part 31d toward the branch part 31b.
- branch parts 20a to 20d, 30a to 30d, and 31a to 31d are provided on refrigerant pipes as illustrated in FIGs. 1 and 2 for the sake of convenience in explaining the refrigerant circuit configuration, this should not be construed restrictively. That is, these branch parts may not necessarily be provided on refrigerant pipes in a clear manner.
- the check valve 11b and the check valve 11c are both connected to the expansion mechanism 5 via the branch part 20a, the check valve 11b and the check valve 11c may be connected to the expansion mechanism 5 directly without passing through a clear branch part 20a.
- branch part 30b and the branch part 31 a are configured as separate branch parts for the convenience of explanation of the refrigerant circuit
- the branch part 30b and the branch part 31a may be configured as an integral branch part, and this configuration does not alter the function of the refrigerant circuit at all, either. The same applies to the other branch parts.
- the outdoor heat exchanger 4 and the indoor heat exchanger 8 correspond to the "heat source-side heat exchanger” and the "use-side heat exchanger", respectively, in the invention according to claim 9 of the present invention.
- the four-way valve 6 and the valves 10a to 10d correspond to the "first flow switching means” and the "second flow switching means", respectively, in the invention according to claim 9 of the present invention.
- the check valves 11a to 11c and the check valves 12a to 12c each correspond to the "third flow switching means" according to claim 9 of the present invention.
- the four-way valve 6 is switched in advance so that the primary-side refrigerant discharged from the compressor 3 flows to the outdoor heat exchanger 4, and that the primary-side refrigerant that has flowed out of the intermediate heat exchanger 7 flows to the compressor 3.
- the valve 10a and the valve 10b are closed, and the valve 10c and the valve 10d are open.
- the primary-side refrigerant in a low-temperature, low-pressure gas state is compressed by the compressor 3, and discharged in a high-temperature, high-pressure state.
- the high-temperature, high-pressure primary-side refrigerant discharged from the compressor 3 flows into the outdoor heat exchanger 4 via the four-way valve 6.
- the primary-side refrigerant that has flowed into the outdoor beat exchanger 4 radiates heat to the outdoor air sent by the fan 4a, and a part or the entire primary-side refrigerant condenses and turns into a two-phase gas-liquid state or liquid state.
- the primary-side refrigerant in a two-phase gas-liquid state or liquid state that has flowed out of the outdoor heat exchanger 4 flows into the expansion mechanism 5, where the primary-side refrigerant is expanded and reduced in pressure and turns into a two-phase gas-liquid state at low temperature and low pressure.
- the primary-side refrigerant in a two-phase gas-liquid state at low temperature and low pressure that has flowed out of the expansion mechanism 5 flows into the intermediate heat exchanger 7.
- the primary-side refrigerant in a two-phase gas-liquid state that has flowed into the intermediate heat exchanger 7 passes through the branch part 20a and the check valve 11b, the primary-side refrigerant divides into branch flows at the branch part 20b, and the branch flows flow into the heat transfer unit 7a and the heat transfer unit 7b in parallel, respectively.
- the primary-side refrigerant does not flow in a direction from the branch part 20a toward the branch part 20c owing to the action of the check valve 11c.
- the flows of the primary-side refrigerant in a two-phase gas-liquid state that have flowed into the heat transfer unit 7a and the heat transfer unit 7b absorb heat from the secondary-side refrigerant flowing in counterflow to the primary-side refrigerant, and evaporates and turns into a low-temperature, low-pressure gas state.
- the primary-side refrigerant in a gas state that has flowed out of the heat transfer unit 7a passes though the branch part 20c and the check valve 11a, merges at the branch part 20d with the primary-side refrigerant in a gas state that has flowed out of the heat transfer unit 7b, and the merged primary-side refrigerant flows out of the intermediate heat exchanger 7.
- the primary-side refrigerant in a gas state that has flowed out of the intermediate heat exchanger 7 is sucked into the compressor 3 via the four-way valve 6, and is compressed again.
- the secondary-side refrigerant sent out by driving of the pump 9 flows into the indoor heat exchanger 8.
- the secondary-side refrigerant that has flowed into the indoor heat exchanger 8 cools the indoor air sent by the fan 8a, and flows into the intermediate heat exchanger 7 via the branch part 30a, the valve 10d, and the branch part 30b.
- the secondary-side refrigerant does not flow in a direction from the branch part 30a toward the branch part 30c because the valve 10b is closed. Also, at the branch part 30b, the secondary-side refrigerant does not flow in a direction from the branch part 30b toward the branch part 30d because the valve 10a is closed.
- the secondary-side refrigerant that has flowed into the intermediate heat exchanger 7 divides into branch flows at the branch part 31a, one of which flows into the heat transfer unit 7b, and the other flows into the heat transfer unit 7a via the check valve 12a and the branch unit 31b.
- the secondary-side refrigerant does not flow in a direction from the branch part 31b toward the branch part 31d owing to the action of the check valve 12c.
- the flows of the secondary-side refrigerant that have flowed into the heat transfer unit 7a and the heat transfer unit 7b in parallel are cooled by the primary-side refrigerant in a low-temperature state flowing in counterflow to the secondary-side refrigerant, and flow into the heat transfer unit 7a and the heat transfer unit 7b, respectively.
- the respective flows of the secondary-side refrigerant that have flowed out of the heat transfer unit 7a and the heat transfer unit 7b merge at the branch part 31 c, and the merged secondary-side refrigerant flows out of the intermediate heat exchanger 7 via the check valve 12b and the branch part 31d.
- the secondary-side refrigerant that has flowed out of the intermediate heat exchanger 7 flows into the pump 9 via the branch part 30c, the valve 10c, and the branch part 30d, and is sent out again.
- the secondary-side refrigerant does not flow in a direction from the branch part 30c toward the branch part 30a because the valve 10b is closed.
- the secondary-side refrigerant does not flow in a direction from the branch part 30d toward the branch part 30b because the valve 10a is closed.
- the four-way valve 6 is switched in advance so that the primary-side refrigerant discharged from the compressor 3 flows to the intermediate heat exchanger 7, and that the primary-side refrigerant that has flowed out of the outdoor heat exchanger 4 flows to the compressor 3.
- the valve 10a and the valve 10b are open, and the valve 10c and the valve 10d are closed.
- the primary-side refrigerant in a low-temperature, low-pressure gas state is compressed by the compressor 3, and discharged in a high-temperature, high-pressure state.
- the high-temperature, high-pressure primary-side refrigerant discharged from the compressor 3 flows into the intermediate heat exchanger 7 via the four-way valve 6.
- the primary-side refrigerant that has flowed into the intermediate heat exchanger 7 flows into the heat transfer unit 7b via the branch part 20d, and radiates heat to the secondary-side refrigerant flowing in counterflow to the primary-side refrigerant.
- the primary-side refrigerant does not flow in a direction from the branch part 20d toward the branch part 20c owing to the action of the check valve 11a.
- the primary-side refrigerant that has flowed out of the heat transfer unit 7b flows into the heat transfer unit 7a via the branch part 20b.
- the primary-side refrigerant radiates heat to the secondary-side refrigerant flowing in counterflow to the primary-side refrigerant.
- the primary-side refrigerant does not flow in a direction from the branch part 20b toward the branch part 20a owing to the action of the check valve 11b. In this way, unlike the cooling operation described above, the primary-side refrigerant flows through the heat transfer unit 7b and the heat transfer unit 7a in series.
- the primary-side refrigerant radiates heat to the secondary-side refrigerant, and a part or the entire primary-side refrigerant condenses and turns into a two-phase gas-liquid state or liquid state.
- the primary-side refrigerant in a two-phase gas-liquid state or liquid state that has flowed out of the beat transfer unit 7a flows out of the intermediate heat exchanger 7 via the branch part 20c, the check valve 11c, and the branch part 20a.
- the primary-side refrigerant in a two-phase gas-liquid state or liquid state that has flowed out of the intermediate heat exchanger 7 flows into the expansion mechanism 5, where the primary-side refrigerant is expanded and reduced in pressure and turns into a two-phase gas-liquid state at low temperature and low pressure.
- the primary-side refrigerant in a two-phase gas-liquid state at low temperature and low pressure that has flowed out of the expansion mechanism 5 flows into the outdoor heat exchanger 4.
- the primary-side refrigerant that has flowed into the outdoor heat exchanger 4 absorbs heat from the outdoor air sent by the fan 4a, and evaporates and turns into a low-temperature, low-pressure gas state.
- the primary-side refrigerant in a gas state that has flowed out of the outdoor heat exchanger 4 is sucked into the compressor 3 via the four-way valve 6, and is compressed again.
- the secondary-side refrigerant sent out by driving of the pump 9 flows into the indoor heat exchanger 8.
- the secondary-side refrigerant that has flowed into the indoor heat exchanger 8 heats the indoor air sent by the fan 8a, and flows into the intermediate heat exchanger 7 via the branch part 30a, the valve 10b, and the branch part 30c.
- the secondary-side refrigerant does not flow in a direction from the branch part 30a toward the branch part 30b because the valve 10d is closed. Also, at the branch part 30c, the secondary-side refrigerant does not flow in a direction from the branch part 30c toward the branch part 30d because the valve 10c is closed.
- the secondary-side refrigerant that has flowed into the intermediate heat exchanger 7 flows into the heat transfer unit 7a via the branch part 31d, the check valve 12c, and the branch part 31b, and is heated by the primary-side refrigerant flowing in counterflow to the secondary-side refrigerant.
- the secondary-side refrigerant does not flow in a direction from the branch part 31d toward the branch part 31c owing to the action of the check valve 12b. Also, at the branch part 31b, the secondary-side refrigerant does not flow in a direction from the branch part 31b toward the branch part 31a owing to the action of the check valve 12a.
- the secondary-side refrigerant that has flowed out of the heat transfer unit 7a flows into the heat transfer unit 7b via the branch part 31c, and is heated by the primary-side refrigerant flowing in counterflow to the secondary-side refrigerant.
- the secondary-side refrigerant flows through the heat transfer unit 7a and the heat transfer unit 7b in series.
- the secondary-side refrigerant that has flowed out of the heat transfer unit 7b flows out of the intermediate heat exchanger 7 via the branch part 31a.
- the secondary-side refrigerant that has flowed out of the intermediate heat exchanger 7 flows into the pump 9 via the branch part 30b, the valve 10a, and the branch part 30d, and is sent out again.
- the secondary-side refrigerant does not flow in a direction from the branch part 30b toward the branch part 30a because the valve 10d is closed.
- the secondary-side refrigerant does not flow in a direction from the branch part 30d toward the branch part 30c because the valve 10c is closed.
- FIG. 3 illustrates the temperature relationship between the primary-side refrigerant and the secondary-side refrigerant in the intermediate heat exchanger 7 in the heating operation, in a case where a refrigerant whose discharge pressure is lower than the critical point is used as the primary-side refrigerant in the air-conditioning apparatus according to Embodiment 1 of the present invention.
- FIG. 4 illustrates the temperature relationship between the primary-side refrigerant and the secondary-side refrigerant in the intermediate heat exchanger 7 in the heating operation, in a case where a refrigerant whose discharge pressure is higher than the critical point is used as the primary-side refrigerant in the air-conditioning apparatus.
- the primary-side refrigerant at a high discharge pressure as illustrated in FIG. 4 has high discharge temperature, and does not become a two-phase state in the intermediate heat exchanger 7, resulting in large amount of heat exchange with the secondary-side refrigerant.
- a large target value can be set for the outlet-inlet temperature difference in the intermediate heat exchanger 7 through which the secondary-side refrigerant flows, or for the outlet-inlet temperature difference in the indoor heat exchanger 8, thereby making it possible to reduce the input to the pump 9.
- the primary-side refrigerant flows through the heat transfer unit 7a and the heat transfer unit 7b in parallel, and in the heating operation in which the primary-side refrigerant radiates heat to the secondary-side refrigerant, the primary-side refrigerant flows through the heat transfer unit 7a and the heat transfer unit 7b in series.
- pressure loss exerts a greater influence than heat transfer capacity in the heat absorption process, whereas heat transfer capacity exerts a greater influence than pressure loss in the heat radiation process.
- the primary-side refrigerant performs a heat absorption operation in the intermediate heat exchanger 7, and flows through the heat transfer unit 7a and the heat transfer unit 7b in parallel so that the overall cross-sectional area of the flow path becomes large.
- the primary-side refrigerant performs a heat radiation operation in the intermediate heat exchanger 7, and flows through the heat transfer unit 7a and the heat transfer unit 7b in series so that the overall cross-sectional area of the flow path becomes small.
- flow velocity increases, thereby making it possible to promote heat transfer. Therefore, highly efficient operation is possible in both the cooling operation and the heating operation.
- the heat transfer unit 7a exists in which the flow directions of both the primary-side refrigerant and the secondary-side refrigerant do not change even when the overall cross-sectional area of the flow path in the intermediate heat exchanger 7 changes as cooling and the heating operations are switched. Consequently, it is possible to take measures such as optimization of refrigerant distribution.
- the secondary-side refrigerant flows through the indoor heat exchanger 8 only in one direction, and in either case, heat exchange with the indoor air is performed in the same manner, resulting in high heat exchange efficiency.
- FIGs. 1 and 2 While the air-conditioning apparatus illustrated in FIGs. 1 and 2 is configured so that the intermediate heat exchanger 7 includes two heat transfer units such as the heat transfer unit 7a and the heat transfer unit 7b, this should not be construed restrictively.
- the intermediate heat exchanger 7 may include three or more heat transfer units.
- FIG. 5 illustrates the flow of refrigerant in the cooling operation in a case where the intermediate heat exchanger 7 includes three heat transfer units (heat transfer units 7a to 7c)
- FIG. 6 illustrates the flow of refrigerant in the heating operation in the case of the same configuration.
- the resulting configuration is the same as the configuration illustrated in FIG. 1 and FIG. 2 . That is, letting 2n (n is a natural number not smaller than 1) represent the number of heat transfer units, the number of check valves belonging to the primary-side refrigerant circuit within the intermediate heat exchanger 7 (the check valves 11a to 11c in FIGs. 1 and 2 ), and the number of check valves belonging to the secondary-side refrigerant circuit (the check valves 12a to 12c in FIGs. 1 and 2 ) are each expressed as (2n+1).
- the resulting configuration is the same as the configuration illustrated in FIG. 5 and FIG. 6 . That is, letting (2n+1) represent the number of heat transfer units, the number of check valves belonging to the primary-side refrigerant circuit within the intermediate heat exchanger 7 (the check valves 11a and 11b in FIGs. 5 and 6 ), and the number of check valves belonging to the secondary-side refrigerant circuit (the check valves 12a and 12b in FIGs. 5 and 6 ) are each expressed as 2n. Therefore, the number of check valves to be installed relative to the number of heat transfer units can be reduced in the case where the number of heat transfer units is an odd number.
- the number of heat transfer units in the intermediate heat exchanger 7 is an even number
- the number of the above-mentioned heat transfer units in which the flow directions of both the primary-side refrigerant and the secondary-side refrigerant do not change equals 50 % of the total number of heat transfer units.
- the number of heat transfer units in the intermediate heat exchanger 7 is an odd number, provided that the number is three, the number of heat transfer units in which both of the flow directions do not change equals 33.3 % of the total number of heat transfer units and its ratio becomes the lowest.
- the check valves 11a to 11c and 12a to 12c within the intermediate heat exchanger 7 in the air-conditioning apparatus illustrated in FIGs. 1, 2 , 5, and 6 may be valves that can be opened and closed.
- the valves corresponding to the check valves 11a, 11b, 12a, and 12b may be opened, and the valves corresponding to the check valves 11c and 12c may be closed.
- the open/close states of these valves may be reversed.
- the number of heat transfer units is an odd number, all valves may be opened in the cooling operation, and all valves may be closed in the heating operation.
- the pump 9 may be a pump whose flow rate can be controlled.
- the target value of the outlet-inlet temperature difference of the secondary-side refrigerant in the intermediate heat exchanger 7, or the outlet-inlet temperature difference of the secondary-side refrigerant in the indoor heat exchanger 8 can be made larger in the heating operation than in the cooling operation, thereby enabling an appropriate operation in both the cooling operation and the heating operation.
- valves 10a to 10d used to switch the direction of the secondary-side refrigerant flowing into the intermediate heat exchanger 7
- two three-way valves or one four-way valve may be used to form a circuit for switching the flow path direction. In this case, it is possible to reduce the number of components.
- indoor unit having the indoor heat exchanger 8 is illustrated as an indoor unit as in FIG. 1 or the like, this should not be construed restrictively.
- the number of indoor units may be two or more.
- FIG. 7 is a schematic diagram of an air-conditioning apparatus according to Embodiment 2 of the present invention.
- the air-conditioning apparatus allows each individual indoor unit to freely select a cooling operation or the heating operation as an operation mode, by use of a primary-side refrigerant circuit through which the primary-side refrigerant flows and a secondary-side refrigerant circuit through which the secondary-side refrigerant flows.
- the air-conditioning apparatus includes two refrigerant circuits, a primary-side refrigerant circuit, and a secondary-side refrigerant circuit.
- a primary-side refrigerant such as R410A
- a hydrocarbon refrigerant such as propane
- a natural refrigerant such as carbon dioxide, or the like is used.
- an azeotropic refrigerant mixture such as R410A, or a zeotropic refrigerant mixture such as R407C, R32, and R134a, or R32 and R1234yf.
- the secondary-side refrigerant that flows through the secondary-side refrigerant circuit for example, brine, water, a liquid mixture of brine and water, a liquid mixture of water and an additive having an anti-corrosion effect, or the like is used.
- Use of these kinds of secondary-side refrigerant contributes to improvement of safety because even if the secondary-side refrigerant leaks to the indoor space via an indoor unit C described later, a highly safe refrigerant is used as the secondary-side refrigerant.
- the primary-side refrigerant circuit includes at least a compressor 103, an outdoor heat exchanger 104, expansion mechanisms 105a and 105b, a four-way valve 106, intermediate heat exchangers 107a and 107b, and valves 111a to 111e.
- the primary-side refrigerant circuit is configured by connecting the compressor 103, the four-way valve 106, the outdoor heat exchanger 104, the expansion mechanisms 105a and 105b, the intermediate heat exchangers 107a and 107b, the four-way valve 106, and the compressor 103 in this order by refrigerant pipes.
- the secondary-side refrigerant circuit includes at least the intermediate heat exchangers 107a and 107b, indoor heat exchangers 108n (n is a natural number not smaller than 2, and represents the number of indoor heat exchangers. The same applies hereinafter.
- the secondary-side refrigerant circuit is configured by connecting the pumps 109a and 109b, the indoor heat exchangers 108n, the intermediate heat exchangers 107a and 107b, and the pumps 109a and 109b in this order by refrigerant pipes.
- the primary-side refrigerant that circulates through the primary-side refrigerant circuit, and the secondary-side refrigerant that circulates through the secondary-side refrigerant circuit exchange heat in the intermediate heat exchangers 107a and 107b.
- the air-conditioning apparatus includes an outdoor unit A that is a heat source unit, a plurality of indoor units C1 to C3 (hereinafter, simply referred to as indoor units C when no distinction is made between individual indoor units), and a relay unit B that is interposed between the outdoor unit A and the indoor units C1 to C3.
- the cooling energy or heating energy generated in the outdoor unit A is transmitted to the indoor units C via the relay unit B.
- the outdoor unit A is usually installed in an outdoor space such as the rooftop of a building.
- the outdoor unit A supplies cooling energy or heating energy to the indoor units C via the relay unit B.
- the outdoor unit A includes the compressor 103, the outdoor heat exchanger 104, and the four-way valve 106.
- the compressor 103 sucks the primary-side refrigerant in a gas state, compresses the primary-side refrigerant into a high-temperature, high-pressure state, and discharges the resulting primary-side refrigerant.
- the compressor 103 may be configured by, for example, an inverter compressor or the like whose capacity can be controlled.
- the outdoor heat exchanger 104 functions as a radiator in the cooling operation, and functions as an evaporator in the heating operation.
- the outdoor heat exchanger 104 exchanges heat between the outdoor air supplied from a fan and the primary-side refrigerant.
- the four-way valve 106 switches between the flow of the primary-side refrigerant in the cooling operation (the cooling only operation mode and the cooling main operation mode described later), and the flow of the primary-side refrigerant in the heating operation (the heating only operation mode and the heating main operation mode described later). Specifically, in the cooling operation, the four-way valve 106 switches the refrigerant flow path so that the primary-side refrigerant discharged from the compressor 103 flows to the outdoor heat exchanger 104, and that the primary-side refrigerant that has flowed out of the relay unit B flows to the compressor 103.
- the four-way valve 106 switches the refrigerant flow path so that the primary-side refrigerant discharged from the compressor 103 flows to the relay unit B, and that the primary-side refrigerant that has flowed out of the outdoor heat exchanger 104 flows to the compressor 103.
- the relay unit B is installed at, for example, a position different from the outdoor space and the indoor space, as a separate casing from the outdoor unit A and the indoor units C.
- the relay unit B serves as a relay connecting the outdoor unit A and the indoor units C by refrigerant pipes.
- the relay unit B includes the intermediate heat exchangers 107a and 107b, the expansion mechanisms 105a and 105b, the pumps 109a and 109b, and the valves 110a to 110h, 111a to 111e, and 112na to 112nd.
- the intermediate heat exchangers 107a and 107b are each configured by, for example, a double-pipe heat exchanger, a plate heat exchanger, a micro-channel water heat exchanger, a shell-and-tube heat exchanger, or the like.
- Each of the intermediate heat exchangers 107a and 107b includes a refrigerant flow path through which the primary-side refrigerant flows, and a refrigerant flow path through which the secondary-side refrigerant flows.
- Each of the intermediate heat exchangers 107a and 107b functions as a radiator or an evaporator to exchange heat between the primary-side refrigerant and the secondary-side refrigerant.
- the intermediate heat exchanger 107a is provided between the expansion mechanism 105a and the valve 111c in the primary-side refrigerant circuit, and is provided between the valve 110a and the valve 110b in the secondary-side refrigerant circuit.
- the intermediate heat exchanger 107b is provided between the expansion mechanism 105b and the valve 111 d in the primary-side refrigerant circuit, and is provided between the valve 110e and the valve 110f in the secondary-side refrigerant circuit.
- each of the intermediate heat exchangers 107a and 107b is preferably installed in such an orientation that the primary-side refrigerant flows into each of the intermediate heat exchangers 107a and 107b from the lower side when the primary-side refrigerant absorbs heat, and that the primary-side refrigerant flows into each of the intermediate heat exchangers 107a and 107b from the upper side when the primary-side refrigerant radiates heat.
- the expansion mechanisms 105a and 105b have the function of a pressure reducing/expansion valve in the primary-side refrigerant circuit, and cause the primary-side refrigerant to be reduced in pressure and expand.
- the expansion mechanism 105a is provided between the intermediate heat exchanger 107a and the valve 111 e
- the expansion mechanism 105b is provided between the intermediate heat exchanger 107b and the valve 111e.
- the expansion mechanisms 105a and 105b may each be configured by a mechanism whose opening degree (opening area) can be variably controlled, for example, an electronic expansion valve or the like.
- the valves 111a to 111e are each configured by a two-way valve or the like.
- the valves 111a to 111e each open and close a refrigerant pipe in the primary-side refrigerant circuit, and switch the flow path of the primary-side refrigerant flowing into and flowing out of the relay unit B in the primary-side refrigerant circuit.
- the valve 111a is provided in the refrigerant pipe that connects between the refrigerant pipe connecting the intermediate heat exchanger 107a and the valve 111c, and the refrigerant pipe connecting the valve 111b and the outdoor heat exchanger 104 (or the valve 111e).
- the valve 111b is provided in the refrigerant pipe that connects between the refrigerant pipe connecting the intermediate heat exchanger 107b and the valve 111d, and the refrigerant pipe connecting the valve 111a and the outdoor heat exchanger 104 (or the valve 111e).
- the valve 111c is provided in the refrigerant pipe connecting the four-way valve 106 and the intermediate heat exchanger 107a.
- the valve 111d is provided in the refrigerant pipe connecting the four-way valve 106 and the intermediate heat exchanger 107b.
- the valve 111e is provided in the refrigerant pipe connecting the outdoor heat exchanger 104 and the expansion mechanism 105a (or the expansion mechanism 105b).
- Each of the pumps 109a and 109b pumps and circulates the secondary-side refrigerant within the secondary-side refrigerant circuit.
- the pumps 109a and 109b may each be configured by, for example, a pump or the like whose capacity can be controlled.
- the refrigerant pipe connected to the discharge side of the pump 109a divides into branches, which are respectively connected to the valves 1121a, 1122a, and 1123a.
- the refrigerant pipe connected to the suction side of the pump 109a is connected to the valve 110a.
- the refrigerant pipe connected to the discharge side of the pump 109b divides into branches, which are respectively connected to the valves 1121b, 1122b, and 1123b.
- the refrigerant pipe connected to the suction side of the pump 109b is connected to the valve 110e.
- the valves 110a to 110h are each configured by a two-way valve or the like.
- the valves 110a to 110h each open and close a refrigerant pipe, and switch the flow path of the secondary-side refrigerant sent to each of the pumps 109a and 109b.
- the valve 110a is provided in the refrigerant pipe connecting the pump 109a and the intermediate heat exchanger 107a.
- the refrigerant pipe connected to one side of the valve 110b is connected to the intermediate heat exchanger 107a, and the refrigerant pipe connected to the other side divides into branches, which are respectively connected to the valves 1121c, 1122c, and 1123c.
- the valve 110c is provided in the refrigerant pipe that connects between the refrigerant pipe connecting the pump 109a and the valve 110a, and the refrigerant pipe connecting the intermediate heat exchanger 107a and the valve 110b.
- the valve 110d is provided in the refrigerant pipe that connects between the refrigerant pipe connecting the intermediate heat exchanger 107a and the valve 110a, and the refrigerant pipe connecting the valve 110b and each of the valves 1121c, 1122c, and 1123c.
- the valve 110e is provided in the refrigerant pipe connecting the pump 109b and the intermediate heat exchanger 107b.
- the refrigerant pipe connected to one side of the valve 110f is connected to the intermediate heat exchanger 107b, and the refrigerant pipe connected to the other side divides into branches, which are respectively connected to the valves 1121 d, 1122d, and 1123d.
- the valve 110g is provided in the refrigerant pipe that connects between the refrigerant pipe connecting the pump 109b and the valve 110e, and the refrigerant pipe connecting the intermediate heat exchanger 107b and the valve 110f.
- the valve 110h is provided in the refrigerant pipe that connects between the refrigerant pipe connecting the intermediate heat exchanger 107b and the valve 110e, and the refrigerant pipe connecting the valve 110f and each of the valves 1121d, 1122d, and 1123d.
- the valves 112na to 112nd (n is a natural number not smaller than 2) switch the flow path of the secondary-side refrigerant sent to the indoor heat exchangers 108n of the indoor units C1 to C3.
- the opening degree (opening area) of the valves 112na to 112nd By adjusting the opening degree (opening area) of the valves 112na to 112nd, the flow rate of the secondary-side refrigerant flowing to the indoor heat exchangers 108n can be controlled.
- the indoor units C1 to C3 include indoor heat exchangers 1081, 1082, and 1083, respectively.
- the indoor units C1 to C3 perform air conditioning by performing cooling or heating for the indoor space in which the indoor units C1 to C3 are provided.
- the indoor heat exchangers 108n (n is a natural number not smaller than 2) function as a radiator in the heating operation and function as an evaporator in the cooling operation.
- the indoor heat exchangers 108n exchange heat between the indoor air supplied from a fan and the secondary-side refrigerant, and generates the heating air or cooling air to be supplied to the indoor space.
- the refrigerant pipe connected to one side of the indoor heat exchanger 1081 divides into branches, which are respectively connected to the valves 1121a and 1121b.
- the refrigerant pipe connected to the other side divides into branches, which are respectively connected to the valves 1121c and 1121 d.
- the refrigerant pipe connected to one side of the indoor heat exchanger 1082 divides into branches, which are respectively connected to the valves 1122a and 1122b.
- the refrigerant pipe connected to the other side divides into branches, which are respectively connected to the valves 1122c and 1122d.
- the refrigerant pipe connected to one side of the indoor heat exchanger 1083 divides into branches, which are respectively connected to the valves 1123a and 1123b.
- the refrigerant pipe connected to the other side divides into branches, which are respectively connected to the valves 1123c and 1123d.
- the number of indoor units C connected is three in FIG. 7 , this should not be construed restrictively.
- the number of indoor units C connected may be other than three.
- the outdoor heat exchanger 104 and the indoor heat exchangers 108n correspond to the "heat source-side heat exchanger” and the "use-side heat exchangers”, respectively, in the invention according to claim 1 of the present invention.
- the four-way valve 106, the valves 111a to 111e, the valves 110a to 110h, and the valves 112na to 112nd correspond to the "first flow switching means", the "second flow switching means", the "third flow switching means", and the "fourth flow switching means", respectively, in the invention according to claim 1 of the present invention.
- Operation modes performed by the air-conditioning apparatus according to Embodiment 2 include a cooling only operation mode in which all of the indoor units C perform a cooling operation, a heating only operation mode in which all of the indoor units C perform a heating operation, a cooling main operation mode which allows a cooling operation or a heating operation to be selected for each individual indoor unit C and in which the cooling load is greater than the heating load, and a heating main operation mode which allows a cooling operation or a heating operation to be selected for each individual indoor unit C and in which the heating load is greater than the cooling load.
- the operation modes will be described together with the flows of the primary-side refrigerant and secondary-side refrigerant.
- FIG. 8 is a refrigerant circuit diagram illustrating the flows of the primary-side refrigerant and secondary-side refrigerant in the cooling only operation mode of the air-conditioning apparatus according to Embodiment 2 of the present invention.
- pipes indicated by thick lines represent pipes through which the primary-side refrigerant and the secondary-side refrigerant flow.
- FIG. 8 the flow direction of the primary-side refrigerant is indicated by solid arrows, and the flow direction of the secondary-side refrigerant is indicated by broken arrows.
- FIGs. 9 to 11 the cooling only operation mode will be described with reference to FIG. 8 .
- the four-way valve 106 is switched in advance so that the primary-side refrigerant discharged from the compressor 103 flows to the outdoor heat exchanger 104, and that the primary-side refrigerant that has flowed out of the relay unit B flows to the compressor 103, and the valves 111a and 111b are closed and the valves 111c to 111e are open.
- the valves 110a, 110b, 110e, and 110f are closed, the valves 110c, 110d, 110g, and 110h are open, and the valves 112na to 112nd are open.
- the primary-side refrigerant in a low-temperature, low-pressure gas state is compressed by the compressor 103, and discharged in a high-temperature, high-pressure state.
- the primary-side refrigerant flows into the outdoor heat exchanger 104 via the four-way valve 106, where the primary-side refrigerant radiates heat to the outdoor air, and a part or the entire primary-side refrigerant condenses and turns into a two-phase gas-liquid state or liquid state.
- the primary-side refrigerant in a two-phase gas-liquid state or liquid state that has flowed out of the outdoor heat exchanger 104 flows out of the outdoor unit A, and flows into the relay unit B.
- the primary-side refrigerant After the primary-side refrigerant that has flowed into the relay unit B passes through the valve 111e, the primary-side refrigerant divides into branch flows.
- the branch flows flow into the expansion mechanisms 105a and 105b, undergo expansion and pressure reduction, turn into a two-phase gas-liquid state at low temperature and low pressure, and flow into the intermediate heat exchangers 107a and 107b in parallel, respectively.
- the merged primary-side refrigerant flows out of the relay unit B, and flows into the outdoor unit A.
- the primary-side refrigerant in a gas state that has flowed into the outdoor unit A is sucked into the compressor 103 via the four-way valve 106, and is compressed again.
- the secondary-side refrigerant at low temperature sent out by driving of the pump 109a divides into branch flows.
- the branch flows flow out of the relay unit B after passing through the valves 1121a, 1122a, and 1123a, and flow into the indoor heat exchanger 1081 of the indoor unit C1, the indoor heat exchanger 1082 of the indoor unit C2, and the indoor heat exchanger 1083 of the indoor unit C3, respectively.
- the secondary-side refrigerant at low temperature sent out by driving of the pump 109b divides into branch flows.
- the branch flows flow out of the relay unit B after passing through the valves 1121b, 1122b, and 1123b, and flow into the indoor heat exchanger 1081 of the indoor unit C1, the indoor heat exchanger 1082 of the indoor unit C2, and the indoor heat exchanger 1083 of the indoor unit C3, respectively.
- the flows of the secondary-side refrigerant that have flowed into the indoor heat exchangers 1081, 1082, and 1083 cool the indoor air and turn into a high-temperature state, flow out of the indoor units C1, C2, and C3, respectively, and flow into the relay unit B.
- the other flow of the secondary-side refrigerant which has passed through the valve 1121d after flowing out of the indoor heat exchanger 1081, flowing into the relay unit B, and dividing into branch flows, the other flow of the secondary-side refrigerant which has passed through the valve 1122d after flowing out of the indoor heat exchanger 1082, flowing into the relay unit B, and dividing into branch flows, and the other flow of the secondary-side refrigerant which has passed through the valve 1123d after flowing out of the indoor heat exchanger 1083, flowing into the relay unit B, and dividing into branch flows, merge, and the merged secondary-side refrigerant flows into the intermediate heat exchanger 107b via the valve 110h.
- the flows of the secondary-side refrigerant that have flowed into the intermediate heat exchangers 107a and 107b are cooled by the primary-side refrigerant in a low-temperature state flowing in counterflow to the secondary-side refrigerant, and flow into the intermediate heat exchangers 107a and 107b, respectively.
- the flows of the secondary-side refrigerant that have flowed out of the intermediate heat exchangers 107a and 107b flow into the pumps 109a and 109b via the valves 110c and 110g, respectively, and are sent out again.
- FIG. 9 is a refrigerant circuit diagram illustrating the flows of the primary-side refrigerant and secondary-side refrigerant in the heating only operation mode of the air-conditioning apparatus according to Embodiment 2 of the present invention.
- the heating only operation mode will be described with reference to FIG. 9 .
- the four-way valve 106 is switched in advance so that the primary-side refrigerant discharged from the compressor 103 flows to the relay unit B, and that the primary-side refrigerant that has flowed out of the outdoor heat exchanger 104 flows to the compressor 103, and the valves 111a and 111b are closed and the valves 111c to 111e are open.
- the valves 110a, 110b, 110e, and 110f are open, the valves 110c, 110d, 110g, and 110h are closed, and the valves 112na to 112nd are open.
- the primary-side refrigerant in a low-temperature, low-pressure gas state is compressed by the compressor 103, and discharged in a high-temperature, high-pressure state.
- the primary-side refrigerant flows out of the outdoor unit A via the four-way valve 106, and flows into the relay unit B.
- the primary-side refrigerant that has flowed into the relay unit B divides into branch flows, and the branch flows flow into the intermediate heat exchangers 107a and 107b in parallel via the valves 111c and 111d, respectively.
- the flows of the primary-side refrigerant in a high-temperature, high-pressure state that have flowed into the intermediate heat exchangers 107a and 107b radiate heat to the secondary-side refrigerant flowing in counterflow to the primary-side refrigerant, and a part or the entire primary-side refrigerant condenses and turns into a two-phase gas-liquid state or liquid state.
- the flows of the primary-side refrigerant in a two-phase gas-liquid state or liquid state that have flowed out of the intermediate heat exchangers 107a and 107b flow into the expansion mechanisms 105a and 105b, respectively, where the flows of the primary-side refrigerant are expanded and reduced in pressure and turn into a two-phase gas-liquid state at low temperature and low pressure, and then merge.
- the merged primary-side refrigerant flows out of the relay unit B via the valve 111e, and flows into the outdoor unit A.
- the primary-side refrigerant is sucked into the compressor 103 via the four-way valve 106, and is compressed again.
- the secondary-side refrigerant at high temperature sent out by driving of the pump 109a divides into branch flows.
- the branch flows flow out of the relay unit B after passing through the valves 1121a, 1122a, and 1123a, and flow into the indoor heat exchanger 1081 of the indoor unit C1, the indoor heat exchanger 1082 of the indoor unit C2, and the indoor beat exchanger 1083 of the indoor unit C3, respectively.
- the secondary-side refrigerant at high temperature sent out by driving of the pump 109b divides into branch flows.
- the branch flows flow out of the relay unit B after passing through the valves 1121b, 1122b, and 1123b, and flow into the indoor heat exchanger 1081 of the indoor unit C1, the indoor heat exchanger 1082 of the indoor unit C2, and the indoor heat exchanger 1083 of the indoor unit C3, respectively.
- the flows of the secondary-side refrigerant that have flowed into the indoor heat exchangers 1081, 1082, and 1083 heat the indoor air and turn into a low-temperature state, flow out of the indoor units C1, C2, and C3, respectively, and flow into the relay unit B.
- the other flow of the secondary-side refrigerant which has passed through the valve 1121d after flowing out of the indoor heat exchanger 1081, flowing into the relay unit B, and dividing into branch flows, the other flow of the secondary-side refrigerant which has passed through the valve 1122d after flowing out of the indoor heat exchanger 1082, flowing into the relay unit B, and dividing into branch flows, and the other flow of the secondary-side refrigerant which has passed through the valve 1123d after flowing out of the indoor heat exchanger 1083, flowing into the relay unit B, and dividing into branch flows, merge, and the merged secondary-side refrigerant flows into the intermediate heat exchanger 107b via the valve 110f.
- the flows of the secondary-side refrigerant that have flowed into the intermediate heat exchangers 107a and 107b are heated by the primary-side refrigerant in a high-temperature state flowing in counterflow to the secondary-side refrigerant, and flow out of the intermediate heat exchangers 107a and 107b, respectively.
- the flows of the secondary-side refrigerant that have flowed out of the intermediate heat exchangers 107a and 107b flow into the pumps 109a and 109b via the valves 110a and 110e, respectively, and are sent out again.
- FIG. 10 is a refrigerant circuit diagram illustrating the flows of the primary-side refrigerant and secondary-side refrigerant in the cooling main operation mode of the air-conditioning apparatus according to Embodiment 2 of the present invention.
- the cooling main operation mode will be described with reference to FIG. 10 .
- the four-way valve 106 is switched in advance so that the primary-side refrigerant discharged from the compressor 103 flows to the outdoor heat exchanger 104, and that the primary-side refrigerant that has flowed out of the relay unit B flows to the compressor 103, and the valves 111a, 111d, and 111e are closed and the valves 111b and 111c are open.
- the valves 110a, 110b, 110g, and 110h are closed, and the valves 110c, 110d, 110e, and 110f are open.
- the valves 1121a, 1121c, 1122b, 1122d, 1123b, and 1123d are closed, and the valves 1121b, 1121d, 1122a, 1122c, 1123a, and 1123c are open.
- the primary-side refrigerant in a low-temperature, low-pressure gas state is compressed by the compressor 103, and discharged in a high-temperature, high-pressure state.
- the primary-side refrigerant flows into the outdoor heat exchanger 104 via the four-way valve 106, where the primary-side refrigerant radiates heat to the outdoor air, and a part of the primary-side refrigerant condenses and turns into a two-phase gas-liquid state.
- the primary-side refrigerant in a two-phase gas-liquid state that has flowed out of the outdoor heat exchanger 104 flows out of the outdoor unit A, and flows into the relay unit B.
- the primary-side refrigerant that has flowed out of the intermediate heat exchanger 107b passes through the expansion mechanism 105b and the expansion mechanism 105a the primary-side refrigerant is expanded and reduced in pressure, turns into a two-phase gas-liquid state at low temperature and low pressure, and flows into the intermediate heat exchanger 107a.
- the primary-side refrigerant in a two-phase gas-liquid state that has flowed into the intermediate heat exchanger 107a absorbs heat from the secondary-side refrigerant flowing in counterflow to the primary-side refrigerant, and evaporates and turns into a low-temperature, low-pressure gas state.
- the primary-side refrigerant in a low-temperature, low-pressure gas state that has flowed out of the intermediate heat exchanger 107a flows out of the relay unit B via the valve 111c, and flows into the outdoor unit A.
- the primary-side refrigerant in a gas state that has flowed into the outdoor unit A is sucked into the compressor 103 via the four-way valve 106, and is compressed again.
- the secondary-side refrigerant at low temperature sent out by driving of the pump 109a divides into branch flows.
- the branch flows flow out of the relay unit B after passing through the valves 1122a and 1123a, and flow into the indoor heat exchanger 1082 of the indoor unit C2, and the indoor heat exchanger 1083 of the indoor unit C3, respectively.
- the flows of the secondary-side refrigerant that have flowed into the indoor heat exchangers 1082 and 1083 cool the indoor air and turn into a high-temperature state, flow out of the indoor units C2 and C3, respectively, and flow into the relay unit B.
- the secondary-side refrigerant that has flowed into the intermediate heat exchanger 107a is cooled by the primary-side refrigerant in a low-temperature state flowing in counterflow to the secondary-side refrigerant, and flows out of the intermediate heat exchanger 107a.
- the secondary-side refrigerant that has flowed out of the intermediate heat exchanger 107a flows into the pump 109a via the valve 110c, and is sent out again.
- the secondary-side refrigerant at high temperature sent out by driving of the pump 109b flows out of the relay unit B after passing through the valve 1121b, and flows into the indoor heat exchanger 1081 of the indoor unit C1.
- the secondary-side refrigerant that has flowed into the indoor heat exchanger 1081 heats the indoor air and turn into a low-temperature state, flow out of the indoor unit C1, and flows into the relay unit B.
- the secondary-side refrigerant that has flowed into the intermediate heat exchanger 107b is heated by the primary-side refrigerant in a high-temperature state flowing in counterflow to the secondary-side refrigerant, and flows out of the intermediate heat exchanger 107b.
- the secondary-side refrigerant that has flowed out of the intermediate heat exchanger 107b flows into the pump 109b via the valve 110e, and is sent out again.
- FIG. 11 is a refrigerant circuit diagram illustrating the flows of the primary-side refrigerant and secondary-side refrigerant in the heating main operation mode of the air-conditioning apparatus according to Embodiment 2 of the present invention.
- the heating main operation mode will be described with reference to FIG. 11 .
- FIG. 11 it is assumed that the indoor units C1 and C2 perform a heating operation, and the indoor unit C3 performs a cooling operation.
- the four-way valve 106 is switched in advance so that the primary-side refrigerant discharged from the compressor 103 flows to the relay unit B, and that the primary-side refrigerant that has flowed out of the outdoor heat exchanger 104 flows to the compressor 103, and the valves 111a and 111d are open and the valves 111b, 111c, and 111e are closed.
- the valves 110a, 110b, 110g, and 110h are closed, and the valves 110c to 110f are open.
- the valves 1121a, 1121c, 1122a, 1122c, 1123b, and 1123d are closed, and the valves 1121b, 1121d, 1122b, 1122d, 1123a, and 1123c are open.
- the primary-side refrigerant in a low-temperature, low-pressure gas state is compressed by the compressor 103, and discharged in a high-temperature, high-pressure state.
- the primary-side refrigerant flows out of the outdoor unit A via the four-way valve 106, and flows into the relay unit B.
- the primary-side refrigerant that has flowed out of the intermediate heat exchanger 107b passes through the expansion mechanism 105b and the expansion mechanism 105a, the primary-side refrigerant is expanded and reduced in pressure, turns into a two-phase gas-liquid state at low temperature and low pressure, and flows into the intermediate heat exchanger 107a.
- the primary-side refrigerant in a two-phase gas-liquid state that has flowed into the intermediate heat exchanger 107a absorbs heat from the secondary-side refrigerant flowing in counterflow to the primary-side refrigerant, and partially evaporates.
- the primary-side refrigerant that has flowed out of the intermediate heat exchanger 107a flows out of the relay unit B via the valve 111a, and flows into the outdoor unit A.
- the primary-side refrigerant that has flowed into the outdoor unit A flows into the outdoor heat exchanger 104, absorbs heat from the indoor air, and evaporates and turns into a low-temperature, low-pressure gas state.
- the primary-side refrigerant is sucked into the compressor 103 via the four-way valve 106, and is compressed again.
- the secondary-side refrigerant at low temperature sent out by driving of the pump 109a flows out of the relay unit B after passing through the valve 1123a, and flows into the indoor heat exchanger 1083 of the indoor unit C3.
- the secondary-side refrigerant that has flowed into the indoor heat exchanger 1083 cools the indoor air and turn into a high-temperature state, flows out of the indoor unit C3, and flows into the relay unit B.
- the secondary-side refrigerant that has flowed into the intermediate heat exchanger 107a is cooled by the primary-side refrigerant in a low-temperature state flowing in counterflow to the secondary-side refrigerant, and flows out of the intermediate heat exchanger 107a.
- the secondary-side refrigerant that has flowed out of the intermediate heat exchanger 107a flows into the pump 109a via the valve 110a, and is sent out again.
- the secondary-side refrigerant at high temperature sent out by driving of the pump 109b divides into branch flows.
- the branch flows flow out of the relay unit B after passing through the valves 1121b and 1122b, and flow into the indoor heat exchanger 1081 of the indoor unit C1, and the indoor heat exchanger 1082 of the indoor unit C2, respectively.
- the flows of the secondary-side refrigerant that have flowed into the indoor heat exchangers 1081 and 1082 heat the indoor air and turn into a low-temperature state, flow out of the indoor units C1 and C2, respectively, and flow into the relay unit B.
- the secondary-side refrigerant that has flowed into the intermediate heat exchanger 107b is heated by the primary-side refrigerant in a high-temperature state flowing in counterflow to the secondary-side refrigerant, and flows out of the intermediate heat exchanger 107b.
- the secondary-side refrigerant that has flowed out of the intermediate heat exchanger 107b flows into the pump 109b via the valve 110e, and is sent out again.
- the primary-side refrigerant and the secondary-side refrigerant flow in counterflow directions in both of the intermediate heat exchangers 107a and 107b. Therefore, thermal effect of the primary-side refrigerant and the secondary-side refrigerant is efficiently exerted, thereby making it possible to reduce the input to each of the pumps 109a and 109b.
- the discharge temperature of the refrigerant is higher than that of a refrigerant whose discharge pressure is lower than the critical point, and the refrigerant does not become a two-phase gas-liquid state. Therefore, the target value of the outlet-inlet temperature difference of the secondary-side refrigerant within the intermediate heat exchanger can be set to a large value, thereby making it possible to reduce the input to the pump.
- a zeotropic refrigerant mixture is used as the primary-side refrigerant, because a zeotropic refrigerant mixture undergoes a temperature change when its phase changes, as compared with a case where a single refrigerant or azeotropic refrigerant mixture that does not undergo a temperature change when its phase changes is used, heat exchange can be performed efficiently when the primary-side refrigerant and the secondary-side refrigerant are made to flow in counterflow directions in the intermediate heat exchanger.
- valves 110a to 110d used to switch the direction of the secondary-side refrigerant flowing into the intermediate heat exchanger 107a
- the four valves 110e to 110h used to switch the direction of the secondary-side refrigerant flowing into the intermediate heat exchanger 107b
- two three-way valves or one four-way valve may be used to form a circuit for switching the flow path direction. In this case, it is possible to reduce the number of components.
- valves 112na and 112nb used to switch the direction of the secondary-side refrigerant flowing into the indoor heat exchangers 108n may be configured as one three-way valve, in which case it is possible to reduce the number of components.
- valves 112nc and 112nd used to switch the direction of the secondary-side refrigerant that has flowed out of the indoor heat exchangers 108n may be configured as one three-way valve, in which case it is possible to reduce the number of components.
- Embodiment 3 An air-conditioning apparatus according to Embodiment 3 will be described while mainly focusing on differences from the air-conditioning apparatus according to Embodiment 2.
- FIG. 12 is a schematic diagram of an air-conditioning apparatus according to Embodiment 3 of the present invention.
- the outdoor unit A includes the compressor 103, the outdoor heat exchanger 104, the four-way valve 106, and a flow switching unit 141 including check valves 113a to 113d.
- the flow switching unit 141 including the check valves 113a to 113d has the function of causing the primary-side refrigerant flowing within the refrigerant pipes connecting the outdoor unit A and the relay unit B to flow in a certain direction.
- the check valve 113a is provided in the refrigerant pipe connecting the four-way valve 106 and each of the valves 111c and 111d, and causes the primary-side refrigerant to flow only in a direction from each of the valves 111c and 111d toward the four-way valve 106.
- the check valve 113b is provided in the refrigerant pipe connecting the outdoor heat exchanger 104 and the valve 111f described later, and causes the primary-side refrigerant to flow only in a direction from the outdoor heat exchanger 104 toward the valve 111f.
- the check valve 113c is provided in the refrigerant pipe that connects between the refrigerant pipe connecting the four-way valve 106 and the check valve 113a, and the refrigerant pipe connecting the check valve 113b and the valve 111f, and causes the primary-side refrigerant to flow only in a direction from the refrigerant pipe connecting the four-way valve 106 and the check valve 113a toward the refrigerant pipe connecting the check valve 113b and the valve 111f.
- the check valve 113d is provided in the refrigerant pipe that connects between the refrigerant pipe connecting the check valve 113a and each of the valves 111c and 111d, and the refrigerant pipe connecting the indoor heat exchanger 104 and the check valve 113b, and causes the primary-side refrigerant to flow only in a direction from the refrigerant pipe connecting the check valve 113a and each of the valves 111c and 111d toward the refrigerant pipe connecting the indoor heat exchanger 104 and the check valve 113b.
- the relay unit B includes the intermediate heat exchangers 107a and 107b, the expansion mechanisms 105a and 105b, the pumps 109a and 109b, the valves 110a to 1110h, 111a to 111f, and 112na to 112nd, and a bypass pipe 142.
- the valve 111f is configured by a two-way valve or the like.
- the valve 111f is provided in the refrigerant pipe between the valve 111e, and the point where the refrigerant pipe into which refrigerant pipes connected to the valves 111a and 111b merge connects with the refrigerant pipe connecting the check valve 113b and the valve 111e.
- the bypass pipe 142 is a refrigerant pipe that connects between the refrigerant pipe connecting the check valve 113a and each of the valves 111c and 111d, and the refrigerant pipe connecting the valve 111e and the valve 111f.
- the flow of the secondary-side refrigerant is the same as that in Embodiment 1.
- FIG. 13 is a refrigerant circuit diagram illustrating the flows of the primary-side refrigerant and secondary-side refrigerant in the cooling only operation mode of the air-conditioning apparatus according to Embodiment 3 of the present invention.
- pipes indicated by thick lines represent pipes through which the primary-side refrigerant and the secondary-side refrigerant flow.
- the flow direction of the primary-side refrigerant is indicated by solid arrows, and the flow direction of the secondary-side refrigerant is indicated by broken arrows.
- FIGs. 14 to 16 the cooling only operation mode will be described with reference to FIG. 13 .
- the four-way valve 106 is switched in advance so that the primary-side refrigerant discharged from the compressor 103 flows to the outdoor heat exchanger 104, and that the primary-side refrigerant that has flowed out of the relay unit B flows to the compressor 103, and the valves 111a and 111b are closed and the valves 111c to 111f are open.
- the valves 110a, 110b, 110e, and 110f are closed, the valves 110c, 110d, 110g, and 110h are open, and the valves 112na to 112nd are open.
- the primary-side refrigerant in a low-temperature, low-pressure gas state is compressed by the compressor 103, and discharged in a high-temperature, high-pressure state.
- the primary-side refrigerant flows into the outdoor heat exchanger 104 via the four-way valve 106, where the primary-side refrigerant radiates heat to the outdoor air, and a part or the entire primary-side refrigerant condenses and turns into a two-phase gas-liquid state or liquid state.
- the primary-side refrigerant in a two-phase gas-liquid state or liquid state that has flowed out of the outdoor heat exchanger 104 flows out of the outdoor unit A via the check valve 113b, and flows into the relay unit B.
- the primary-side refrigerant that has flowed into the relay unit B passes through the valves 111f and the valve 111e, the primary-side refrigerant divides into branch flows.
- the branch flows flow into the expansion mechanisms 105a and 105b, undergo expansion and pressure reduction, turn into a two-phase gas-liquid state at low temperature and low pressure, and flow into the intermediate heat exchangers 107a and 107b in parallel, respectively.
- the flows of the primary-side refrigerant in a two-phase gas-liquid state that have flowed into the intermediate heat exchangers 107a and 107b absorb heat from the secondary-side refrigerant flowing in counterflow to the primary-side refrigerant, and evaporate and turn into a low-temperature, low-pressure gas state.
- the flows of the primary-side refrigerant that have flowed out of the intermediate heat exchangers 107a and 107b merge after passing through the valves 111c and 111d, respectively.
- the merged primary-side refrigerant flows out of the relay unit B, and flows into the outdoor unit A.
- the primary-side refrigerant in a gas state that has flowed into the outdoor unit A is sucked into the compressor 103 via the check valve 113a and the four-way valve 106, and is compressed again.
- FIG. 14 is a refrigerant circuit diagram illustrating the flows of the primary-side refrigerant and secondary-side refrigerant in the heating only operation mode of the air-conditioning apparatus according to Embodiment 3 of the present invention.
- the heating only operation mode will be described with reference to FIG. 14 .
- the four-way valve 106 is switched in advance so that the primary-side refrigerant discharged from the compressor 103 flows to the relay unit B, and that the primary-side refrigerant that has flowed out of the outdoor heat exchanger 104 flows to the compressor 103, and the valves 111a, 111b, and 111e are open and the valves 111c, 111d, and 111f are closed.
- the valves 110a, 110b, 110e, and 110f are open, the valves 110c, 110d, 110g, and 110h are closed, and the valves 112na to 112nd are open.
- the primary-side refrigerant in a low-temperature, low-pressure gas state is compressed by the compressor 103, and discharged in a high-temperature, high-pressure state.
- the primary-side refrigerant flows out of the outdoor unit A via the four-way valve 106 and the check valve 113c, and flows into the relay unit B.
- the primary-side refrigerant that has flowed into the relay unit B divides into branch flows, and the branch flows flow into the intermediate heat exchangers 107a and 107b in parallel via the valves 111a and 111b, respectively.
- the flows of the primary-side refrigerant in a high-temperature, high-pressure state that have flowed into the intermediate heat exchangers 107a and 107b radiate heat to the secondary-side refrigerant flowing in counterflow to the primary-side refrigerant, and a part or the entire primary-side refrigerant condenses and turns into a two-phase gas-liquid state or liquid state.
- the flows of the primary-side refrigerant in a two-phase gas-liquid state or liquid state that have flowed out of the intermediate heat exchangers 107a and 107b flow into the expansion mechanisms 105a and 105b, respectively, undergo expansion and pressure reduction, turn into a two-phase gas-liquid state at low temperature and low pressure, and then merge.
- the merged primary-side refrigerant passes through the valve 111e, and flows out of the relay unit B after flowing through the bypass pipe 142, and flows into the outdoor unit A.
- the primary-side refrigerant is sucked into the compressor 103 via the four-way valve 106, and is compressed again.
- FIG. 15 is a refrigerant circuit diagram illustrating the flows of the primary-side refrigerant and secondary-side refrigerant in the cooling main operation mode of the air-conditioning apparatus according to Embodiment 3 of the present invention.
- the cooling main operation mode will be described with reference to FIG. 15 .
- FIG. 15 it is assumed that the indoor unit C1 performs a heating operation, and the indoor units C2 and C3 perform a cooling operation.
- the four-way valve 106 is switched in advance so that the primary-side refrigerant discharged from the compressor 103 flows to the outdoor heat exchanger 104, and that the primary-side refrigerant that has flowed out of the relay unit B flows to the compressor 103, and the valves 111a, 111d, 111e, and 111f are closed and the valves 111b and 111c are open.
- the valves 110a, 110b, 110g, and 110h are closed, and the valves 110c, 110d, 110e, and 110f are open.
- the valves 1121a, 1121c, 1122b, 1122d, 1123b, and 1123d are closed, and the valves 1121b, 1121d, 1122a, 1122c, 1123a, and 1123c are open.
- the primary-side refrigerant in a low-temperature, low-pressure gas state is compressed by the compressor 103, and discharged in a high-temperature, high-pressure state.
- the primary-side refrigerant flows into the outdoor heat exchanger 104 via the four-way valve 106, where the primary-side refrigerant radiates heat to the outdoor air, and a part of the primary-side refrigerant condenses and turns into a two-phase gas-liquid state.
- the primary-side refrigerant in a two-phase gas-liquid state that has flowed out of the outdoor heat exchanger 104 flows out of the outdoor unit A via the check valve 113b, and flows into the relay unit B.
- the primary-side refrigerant that has flowed out of the intermediate heat exchanger 107b passes through the expansion mechanism 105b and the expansion mechanism 103a the primary-side refrigerant is expanded and reduced in pressure, turns into a two-phase gas-liquid state at low temperature and low pressure, and flows into the intermediate heat exchanger 107a.
- the primary-side refrigerant in a two-phase gas-liquid state that has flowed into the intermediate heat exchanger 107a absorbs heat from the secondary-side refrigerant flowing in counterflow to the primary-side refrigerant, and evaporates and turns into a low-temperature, low-pressure gas state.
- the primary-side refrigerant in a low-temperature, low-pressure gas state that has flowed out of the intermediate heat exchanger 107a flows out of the relay unit B via the valve 111c, and flows into the outdoor unit A.
- the primary-side refrigerant in a gas state that has flowed into the outdoor unit A is sucked into the compressor 103 via the check valve 113a and the four-way valve 106, and is compressed again.
- FIG. 16 is a refrigerant circuit diagram illustrating the flows of the primary-side refrigerant and secondary-side refrigerant in the heating main operation mode of the air-conditioning apparatus according to Embodiment 3 of the present invention.
- the heating main operation mode will be described with reference to FIG. 16 .
- FIG. 16 it is assumed that the indoor units C1 and C2 perform a heating operation, and the indoor unit C3 performs a cooling operation.
- the four-way valve 106 is switched in advance so that the primary-side refrigerant discharged from the compressor 103 flows to the relay unit B, and that the primary-side refrigerant that has flowed out of the outdoor heat exchanger 104 flows to the compressor 103, and the valves 111a, and 111d to 111f are closed and the valves 111b and 111c are open.
- the valves 110a, 110b, 110g, and 110h are closed, and the valves 110c to 110f are open.
- valves 1121 a, 1121c, 1122a, 1122c, 1123b, and 1123d are closed, and the valves 1121b, 1121d, 1122b, 1122d, 1123a, and 1123c are open.
- the primary-side refrigerant in a low-temperature, low-pressure gas state is compressed by the compressor 103, and discharged in a high-temperature, high-pressure state.
- the primary-side refrigerant flows out of the outdoor unit A via the four-way valve 106 and the check valve 113c, and flows into the relay unit B.
- the primary-side refrigerant that has flowed out of the intermediate heat exchanger 107b passes through the expansion mechanism 105b and the expansion mechanism 105a, the primary-side refrigerant is expanded and reduced in pressure, turns into a two-phase gas-liquid state at low temperature and low pressure, and flows into the intermediate heat exchanger 107a.
- the primary-side refrigerant in a two-phase gas-liquid state that has flowed into the intermediate heat exchanger 107a absorbs heat from the secondary-side refrigerant flowing in counterflow to the primary-side refrigerant, and partially evaporates.
- the primary-side refrigerant that has flowed out of the intermediate heat exchanger 107a flows out of the relay unit B via the valve 111c, and flows into the outdoor unit A.
- the primary-side refrigerant that has flowed into the outdoor unit A flows into the outdoor heat exchanger 104 via the check valve 113d, absorbs heat from the indoor air, and evaporates and turns into a low-temperature, low-pressure gas state.
- the primary-side refrigerant is sucked into the compressor 103 via the four-way valve 106, and is compressed again.
- the primary-side refrigerant flowing through the refrigerant pipes connecting the outdoor unit A and the relay unit B flow in a certain direction, and the refrigerant pipes through which a high-pressure refrigerant and a low-pressure refrigerant flow become fixed. Consequently, of the refrigerant pipes connecting the outdoor unit A and the relay unit B, the wall thickness of the refrigerant pipe through which the low-pressure refrigerant flows can be reduced, thereby enabling cost reduction.
- Embodiment 4 An air-conditioning apparatus according to Embodiment 4 will be described while mainly focusing on differences from the air-conditioning apparatus according to Embodiment 2.
- FIG. 17 is a schematic diagram of an air-conditioning apparatus according to Embodiment 4 of the present invention.
- the intermediate heat exchangers 107a and 107b in the air-conditioning apparatus according to Embodiment 2 are replaced by intermediate heat exchangers 107aa and 107ba, respectively.
- the intermediate heat exchangers 107aa and 107ba are both configured in the same manner as the intermediate heat exchanger 7 in the air-conditioning apparatus according to Embodiment 1.
- heat transfer units 1071a and 1072a, and check valves 132a to 132c and 133a to 133c in the intermediate heat exchanger 107aa correspond to the heat transfer units 7a and 7b, and the check valves 11a to 11c and 12a to 12c in the intermediate heat exchanger 7 in Embodiment 1, respectively.
- Heat transfer units 1071b and 1072b, and check valves 132d to 132f and 133d to 133f in the intermediate heat exchanger 107ba correspond to the heat transfer units 7a and 7b, and the check valves 11a to 11c and 12a to 12c in the intermediate heat exchanger 7 in Embodiment 1, respectively.
- the operation of the air-conditioning apparatus according to Embodiment 4 is the same as that of the air-conditioning apparatus according to Embodiment 2, except for the flow of refrigerant within each of the intermediate heat exchangers 107aa and 107ba. Moreover, provided that the primary-side refrigerant and the secondary-side refrigerant flow out of and flow into the intermediate heat exchanger 107aa and the intermediate heat exchanger 107a in the same direction, the operations in the intermediate heat exchanger 107aa and the intermediate heat exchanger 107a are the same. Accordingly, hereinafter, the operation in the intermediate heat exchanger 107a will be described.
- check valves 132a to 132f and 133a to 133f correspond to the "fifth flow switching means" in the invention according to claim 5 of the present invention.
- FIG. 18 illustrates the flows of the primary-side refrigerant and secondary-side refrigerant in a case where the intermediate heat exchanger 107ba in the air-conditioning apparatus according to Embodiment 4 of the present invention functions as an evaporator.
- pipes indicated by thick lines represent pipes through which the primary-side refrigerant and the secondary-side refrigerant flow.
- FIG. 18 the flow direction of the primary-side refrigerant is indicated by solid arrows, and the flow direction of the secondary-side refrigerant is indicated by broken arrows.
- FIG. 19 the same applies to FIG. 19 .
- the operation in a case where the intermediate heat exchanger 107ba functions as an evaporator will be described with reference to FIG. 18 .
- the primary-side refrigerant in a two-phase gas-liquid state that has flowed into the intermediate heat exchanger 107ba passes through the check valve 132e, the primary-side refrigerant divides into branch flows, and the branch flows flow into the heat transfer unit 1071b and the heat transfer unit 1072b in parallel, respectively. At this time, the primary-side refrigerant does not flow in a direction toward the check valve 132d owing to the action of the check valve 132f.
- the flows of the primary-side refrigerant in a two-phase gas-liquid state that have flowed into the heat transfer unit 1071b and the heat transfer unit 1072b absorb heat from the secondary-side refrigerant flowing in counterflow to the primary-side refrigerant, and partially evaporate, or evaporate and turn into a low-temperature, low-pressure gas state.
- the primary-side refrigerant that has flowed out of the heat transfer unit 1071b passes though the check valve 132d, merges with the primary-side refrigerant that has flowed out of the heat transfer unit 1072b, and flows out of the intermediate heat exchanger 107ba.
- the secondary-side refrigerant that has flowed into the intermediate heat exchanger 107ba divides into branch flows, one of which flows into the heat transfer unit 1072b, and the other flows into the heat transfer unit 1071b via the check valve 133d. At this time, the secondary-side refrigerant does not flow in a direction toward the outlet of the secondary-side refrigerant in the intermediate heat exchanger 107ba owing to the action of the check valve 133f.
- the flows of the secondary-side refrigerant that have flowed into the heat transfer unit 1071b and the heat transfer unit 1072b in parallel are cooled by the primary-side refrigerant in a low-temperature state flowing in counterflow to the secondary-side refrigerant, and flow out of the heat transfer unit 1071b and the heat transfer unit 1072b, respectively.
- the flows of the secondary-side refrigerant that have respectively flowed out of the heat transfer unit 1071b and the heat transfer unit 1072b merge, and the merged secondary-side refrigerant flows out of the intermediate heat exchanger 107ba via the check valve 133e.
- FIG. 19 illustrates the flows of the primary-side refrigerant and secondary-side refrigerant in a case where the intermediate heat exchanger 107ba in the air-conditioning apparatus according to Embodiment 4 of the present invention functions as a radiator.
- pipes indicated by thick lines represent pipes through which the primary-side refrigerant and the secondary-side refrigerant flow.
- FIG. 19 the flow direction of the primary-side refrigerant is indicated by solid arrows, and the flow direction of the secondary-side refrigerant is indicated by broken arrows.
- the operation in a case where the intermediate heat exchanger 107ba functions as a radiator will be described with reference to FIG. 19 .
- the primary-side refrigerant that has flowed into the intermediate heat exchanger 107ba flows into the heat transfer unit 1072b, and radiates heat to the secondary-side refrigerant flowing in counterflow to the primary-side refrigerant. At this time, the primary-side refrigerant does not flow in a direction toward the heat transfer unit 1071b and the check valve 132f owing to the action of the check valve 132d.
- the primary-side refrigerant that has flowed out of the heat transfer unit 1072b flows into the heat transfer unit 1071b.
- the primary-side refrigerant radiates heat to the secondary-side refrigerant flowing in counterflow to the primary-side refrigerant. At this time, the primary-side refrigerant does not flow in a direction toward the outlet of the primary-side refrigerant in the intermediate heat exchanger 107ba owing to the action of the check valve 132e.
- the primary-side refrigerant flows through the heat transfer unit 1072b and the heat transfer unit 1071b in series, and during this process, the primary-side refrigerant radiates heat to the secondary-side refrigerant, and a part or the entire primary-side refrigerant condenses and turns into a two-phase gas-liquid state or liquid state.
- the secondary-side refrigerant that has flowed into the intermediate heat exchanger 107ba flows into the heat transfer unit 1071b via the check valve 133f, and is heated by the primary-side refrigerant flowing in counterflow to the secondary-side refrigerant. At this time, the secondary-side refrigerant does not flow in a direction toward the heat transfer unit 1072b owing to the action of the check valve 133e. The secondary-side refrigerant does not flow in a direction toward the outlet of the secondary-side refrigerant in the intermediate heat exchanger 107ba, either, owing to the action of the check valve 133d.
- the secondary-side refrigerant that has flowed out of the heat transfer unit 1071b flows into the heat transfer unit 1072b, and is heated by the primary-side refrigerant flowing in counterflow to the secondary-side refrigerant. In this way, the secondary-side refrigerant flows through the heat transfer unit 1071b and the heat transfer unit 1072b in series.
- the secondary-side refrigerant that has flowed out of the heat transfer unit 1072b flows out of the intermediate heat exchanger 107ba.
- the intermediate heat exchangers 107aa and 107a both act as the evaporator described above with reference to FIG. 18
- the intermediate heat exchangers 107aa and 107ba both act as the radiator described above with reference to FIG. 19 .
- the intermediate heat exchanger 107aa acts as the evaporator described above with reference to FIG. 18
- the intermediate heat exchanger 107a acts as the radiator described above with reference to FIG. 19 .
- each of the intermediate heat exchangers 107aa and 107a functions as an evaporator where the primary-side refrigerant absorbs heat from the secondary-side refrigerant
- the primary-side refrigerant flows through the heat transfer unit 1071a (1071b) and the heat transfer unit 1072a (1072b) in parallel
- each of the intermediate heat exchangers 107aa and 107a functions as a radiator where the primary-side refrigerant radiates heat to the secondary-side refrigerant
- the primary-side refrigerant flows through the heat transfer unit 1071a (1071b) and the heat transfer unit 1072a (1072b) in series.
- pressure loss exerts a greater influence than heat transfer capacity in the heat absorption process
- heat transfer capacity exerts a greater influence than pressure loss in the heat radiation process.
- the primary-side refrigerant performs a heat absorption operation, and flows through the heat transfer unit 1071 a (1071b) and the heat transfer unit 1072a (1072b) in parallel so that the overall cross-sectional area of the flow path becomes large. Therefore, pressure loss that tends to exert a great influence in the heat absorption process can be reduced, thereby making it possible to reduce the input to the compressor 103.
- the primary-side refrigerant performs a heat radiation operation, and flows through the heat transfer unit 1071a (1071b) and the heat transfer unit 1072a (1072b) in series so that the overall cross-sectional area of the flow path becomes small.
- flow velocity increases, thereby making it possible to promote heat transfer. Therefore, highly efficient operation is possible in each operation mode.
- the secondary-side refrigerant flows through the indoor heat exchangers 108n only in one direction, and in either case, heat exchange with the indoor air is performed in the same manner, resulting in high heat exchange efficiency.
- check valves 132a to 132f and 133a to 133f makes it unnecessary to perform operations other than operations of the four-way valve 106 and each valve, for switching of the overall cross-sectional area of the flow path in each of the intermediate heat exchangers 107aa and 107ba due to switching of operation modes. Consequently, in the vicinity of each of the intermediate heat exchangers 107aa and 107ba, problems such as leakage of refrigerant from valves can be prevented, thereby enabling safe operation.
- the configuration of the intermediate heat exchangers 107aa and 107a of the air-conditioning apparatus according to Embodiment 4 can be also applied to the air-conditioning apparatus according to Embodiment 3.
- the air-conditioning apparatus illustrated in FIG. 17 is configured so that the intermediate heat exchangers 107aa and 107ba each include two heat transfer units such as the heat transfer unit 1071a (1071b) and the heat transfer unit 1072a (1072b), this should not be construed restrictively.
- the intermediate heat exchangers 107aa and 107ba may each include three or more heat transfer units.
- FIG. 20 illustrates a configuration in which the intermediate heat exchangers 107aa and 107a each include three heat transfer units (heat transfer units 1071a to 1073a (1071b to 1073b)).
- the resulting configuration is the same as the configuration illustrated in FIG. 17 .
- 2n (n is a natural number not smaller than 1) represent the number of heat transfer units
- the number of check valves belonging to the primary-side refrigerant circuit within each of the intermediate heat exchangers 107aa and 107ba (the check valves 132a to 132f in FIG. 17 )
- the number of check valves belonging to the secondary-side refrigerant circuit (the check valves 133a to 133f in FIG. 17 ) are each expressed as (2n+1).
- the resulting configuration is the same as the configuration illustrated in FIG. 20 .
- (2n+1) represent the number of heat transfer units
- the number of check valves belonging to the primary-side refrigerant circuit within each of the intermediate heat exchangers 107aa and 107ba (the check valves 132a, 132b, 132d, and 132e in FIG. 20 )
- the number of check valves belonging to the secondary-side refrigerant circuit (the check valves 133a, 133b, 133d, and 133e in FIG. 20 ) are each expressed as 2n.
- the number of check valves to be installed relative to the number of heat transfer units can be reduced in the case where the number of heat transfer units is an odd number.
- the number of the above-mentioned heat transfer units in which the flow directions of both the primary-side refrigerant and the secondary-side refrigerant do not change equals 50 % of the total number of heat transfer units.
- the number of heat transfer units in each of the intermediate heat exchangers 107aa and 107ba is an odd number, provided that the number is three, the number of heat transfer units in which both of the flow directions do not change equals 33.3 % of the total number of heat transfer units and its ratio becomes the lowest.
- the check valves inside each of the intermediate heat exchangers 107aa and 107ba in the air-conditioning apparatus illustrated in FIGs. 17 and 20 may be valves that can be opened and closed. In this case, for example, although an operation according to each operation mode becomes necessary, equipment cost can be reduced.
- FIG. 21 is a schematic diagram of an air-conditioning apparatus according to Embodiment 5 of the present invention.
- the flow of the secondary-side refrigerant flowing through the intermediate heat exchanger 107b becomes a certain direction. Accordingly, in a case where the intermediate heat exchanger 107b acts an evaporator, the primary-side refrigerant and the secondary-side refrigerant are not in counterflow, resulting in poor efficiency.
- the effect of counterflow is greater in the case where the intermediate heat exchanger 107b acts as a condenser than in the case where the intermediate heat exchanger 107b acts as an evaporator, and of the four operation modes, the intermediate heat exchanger 107b acts as an evaporator only in the cooling only operation mode. Therefore, a cost reduction that more than compensates for a decrease in performance can be expected.
- Such a configuration in which the check valves 110e to 110h are omitted can be also applied to the air-conditioning apparatus according to Embodiment 2.
- FIG. 22 illustrates an installation example of an air-conditioning apparatus according to Embodiment 6 of the present invention.
- the air-conditioning apparatus illustrated in FIG. 22 will be described by way of an example in which the air-conditioning apparatus is the air-conditioning apparatus according to each of Embodiments 2 to 5, and this air-conditioning apparatus is installed in a building or the like having a plurality of floors.
- the outdoor unit A is installed in an outdoor space such as the rooftop of a building 100 illustrated in FIG. 22 .
- the indoor unit C is installed at a position that allows a cooling operation and a heating operation to be performed for the air in the indoor space.
- a plurality of indoor units C (three indoor units C (indoor units C1 to C3) in FIG. 22 ) are installed in the indoor space on each floor of the building 100.
- the relay unit B is installed in a non-air-conditioned space inside the building 100.
- the relay unit B is connected to the outdoor unit A and each of the indoor units C by refrigerant pipes.
- the relay unit B is installed for each plurality of indoor units C installed on each floor. That is, heat transport between the outdoor unit A and the relay unit B is performed by the primary-side refrigerant, and heat transport between the indoor unit C and the relay unit B is performed by the secondary-side refrigerant.
- the air-conditioning apparatus according to Embodiment 1 may be applied to the air-conditioning apparatus illustrated in FIG. 22 .
- the outdoor unit A corresponds to the portion constituting the primary-side refrigerant circuit in the air-conditioning apparatus according to Embodiment 1 (excluding the intermediate heat exchanger 7)
- the indoor unit C corresponds to a portion constituting the secondary-side refrigerant circuit in the air-conditioning apparatus which has the indoor heat exchanger 8 and the fan 8a.
- the relay unit B corresponds to the intermediate heat exchanger 7 in the air-conditioning apparatus according to Embodiment 1, and a portion constituting the secondary-side refrigerant circuit which has the pump 9 and the valves 10a to 10d.
- the outdoor unit A is installed on the rooftop of the building 100 as illustrated in FIG. 22 , this should not be construed restrictively.
- the outdoor unit A may be installed in the basement of the building 100, in the machine room on each floor, or the like.
- indoor units C While three indoor units C are installed on each floor of the building 100 as illustrated in FIG. 22 , this should not be construed restrictively. For example, one or another number of indoor units C may be installed.
- the secondary-side refrigerant such as water flows through the refrigerant pipe connected to the indoor unit C installed in an indoor space such as a living space. Therefore, leakage of the primary-side refrigerant to the indoor space can be prevented.
- the outdoor unit A and the indoor unit C are installed in places other than an indoor space such as a living space, which allows for easy maintenance of these units.
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Abstract
Description
- The present invention relates to an air-conditioning apparatus that has two refrigerant circuits including a primary-side refrigerant circuit and a secondary-side refrigerant circuit, and causes heat to be exchanged between a primary-side refrigerant and a secondary-side refrigerant in an intermediate heat exchanger.
- As an air-conditioning apparatus in related art, there has been proposed an air-conditioning apparatus capable of simultaneous cooling and the heating operation which "includes a heat source-side refrigerant circuit A having a compressor 11, an outdoor heat exchanger 13, a first refrigerant branch part 21 connected to the compressor 11, a second refrigerant branch part 22 and a third
refrigerant branch part 23 connected to the outdoor heat exchanger 13, a first refrigerant flow control device 24 provided between abranch pipe 40 and the second refrigerant branch part 22, intermediate heat exchangers 25n whose one side is connected to the first refrigerant branch part 21 and the thirdrefrigerant branch part 23 via three-way valves 26n and whose other side is connected to the second refrigerant branch part 22, and second refrigerant flow control devices 27n provided between each of the intermediate heat exchangers 25n and the second refrigerant branch part 22, and a use-side refrigerant circuit Bn having indoor heat exchangers 31n connected to the intermediate heat exchangers 25n, and in which at least one of water and brine circulates through the use-side refrigerant circuit Bn" (see Patent Literature 1). - Patent Literature 1:
WO2009/133640 A (Abstract) - However, the air-conditioning apparatus described in
Patent Literature 1 has the following problem. That is, while the direction of the heat source-side refrigerant flowing through the intermediate heat exchangers changes depending on the operation mode, the flow of the use-side refrigerant is a certain direction. Therefore, appropriate heat exchange efficiency is not obtained in intermediate heat exchangers in which these refrigerants are in parallel flow, which makes it impossible to perform optimum operation in all operation modes. - The present invention has been made in view of the problem mentioned above, and accordingly it is an object of the present invention to provide an air-conditioning apparatus which ensures high heat exchange efficiency even when the direction of a heat source-side refrigerant (primary-side refrigerant) flowing through an intermediate heat exchanger changes, and enables an appropriate operation in any operation mode.
- An air-conditioning apparatus according to the present invention includes a primary-side refrigerant circuit in which a compressor, first flow switching means, a heat source-side heat exchanger, second flow switching means, a plurality of intermediate heat exchangers, and an expansion mechanism are connected by refrigerant pipes, and through which a primary-side refrigerant flows, and a secondary-side refrigerant circuit in which the intermediate heat exchangers, third flow switching means, a pump, fourth flow switching means, and a plurality of use-side heat exchangers are connected by refrigerant pipes, and through which a secondary-side refrigerant different from the primary-side refrigerant flows.
- Each of the intermediate heat exchangers exchanges heat between the primary-side refrigerant and the secondary-side refrigerant. The first flow switching means switches a refrigerant flow path so that the primary-side refrigerant discharged from the compressor flows to each of the intermediate heat exchangers or the heat source-side heat exchanger.
- The second flow switching means switches a flow direction of the primary-side refrigerant flowing into each of the intermediate heat exchangers. The third flow switching means switches a flow direction of the secondary-side refrigerant flowing into each of the intermediate heat exchangers.
- The fourth flow switching means switches a refrigerant flow path to direct one of flows of the secondary-side refrigerant that have flown through the plurality of the intermediate heat exchangers to flow through the corresponding each use-side heat exchanger, so that one of a cooling operation and a heating operation is performed in a selectable manner by each of the use-side heat exchangers.
- The second flow switching means and the third flow switching means each switch a refrigerant flow path so that the primary-side refrigerant and the secondary-side refrigerant are in counterflow in at least one of the intermediate heat exchangers.
- According to the present invention, the primary-side refrigerant and the secondary-side refrigerant are in counterflow in at least one intermediate heat exchanger. Therefore, thermal effect of the primary-side refrigerant and the secondary-side refrigerant is exerted efficiently, thereby making it possible to reduce the input to the pump.
-
- FIG. 1
- is a schematic diagram of an air-conditioning apparatus according to
Embodiment 1 of the present invention, illustrating the flow of a refrigerant in a cooling operation. - FIG. 2
- is a schematic diagram of an air-conditioning apparatus according to
Embodiment 1 of the present invention, illustrating the flow of refrigerant in the heating operation. - FIG. 3
- illustrates the temperature relationship between a primary-side refrigerant and a secondary-side refrigerant in an
intermediate heat exchanger 7 in the heating operation, in a case where a refrigerant whose discharge pressure is lower than the critical point is used as the primary-side refrigerant in the air-conditioning apparatus according toEmbodiment 1 of the present invention. - FIG. 4
- illustrates the temperature relationship between the primary-side refrigerant and the secondary-side refrigerant in the
intermediate heat exchanger 7 in the heating operation, in a case where a refrigerant whose discharge pressure is higher than the critical point is used as the primary-side refrigerant in the air-conditioning apparatus according toEmbodiment 1 of the present invention. - FIG 5
- illustrates the flow of refrigerant in the cooling operation in a case where the
intermediate heat exchanger 7 includes three heat transfer units. - FIG. 6
- illustrates the flow of refrigerant in the heating operation in a case where the
intermediate heat exchanger 7 includes three heat transfer units. - FIG. 7
- is a schematic diagram of an air-conditioning apparatus according to Embodiment 2 of the present invention.
- FIG. 8
- is a refrigerant circuit diagram illustrating the flows of the primary-side refrigerant and secondary-side refrigerant in the cooling only operation mode of the air-conditioning apparatus according to Embodiment 2 of the present invention.
- FIG. 9
- is a refrigerant circuit diagram illustrating the flows of the primary-side refrigerant and secondary-side refrigerant in the heating only operation mode of the air-conditioning apparatus according to Embodiment 2 of the present invention.
- FIG. 10
- is a refrigerant circuit diagram illustrating the flows of the primary-side refrigerant and secondary-side refrigerant in the cooling main operation mode of the air-conditioning apparatus according to Embodiment 2 of the present invention.
- FIG. 11
- is a refrigerant circuit diagram illustrating the flows of the primary-side refrigerant and secondary-side refrigerant in the heating main operation mode of the air-conditioning apparatus according to Embodiment 2 of the present invention.
- FIG. 12
- is a schematic diagram of an air-conditioning apparatus according to Embodiment 3 of the present invention.
- FIG. 13
- is a refrigerant circuit diagram illustrating the flows of the primary-side refrigerant and secondary-side refrigerant in the cooling only operation mode of the air-conditioning apparatus according to Embodiment 3 of the present invention.
- FIG. 14
- is a refrigerant circuit diagram illustrating the flows of the primary-side refrigerant and secondary-side refrigerant in the heating only operation mode of the air-conditioning apparatus according to Embodiment 3 of the present invention.
- FIG. 15
- is a refrigerant circuit diagram illustrating the flows of the primary-side refrigerant and secondary-side refrigerant in the cooling main operation mode of the air-conditioning apparatus according to Embodiment 3 of the present invention.
- FIG. 16
- is a refrigerant circuit diagram illustrating the flows of the primary-side refrigerant and secondary-side refrigerant in the heating main operation mode of the air-conditioning apparatus according to Embodiment 3 of the present invention.
- FIG. 17
- is a schematic diagram of an air-conditioning apparatus according to
Embodiment 4 of the present invention. - FIG. 18
- illustrates the flows of the primary-side refrigerant and secondary-side refrigerant in a case where an intermediate heat exchanger 107ba in the air-conditioning apparatus according to
Embodiment 4 of the present invention functions as an evaporator. - FIG. 19
- illustrates the flows of the primary-side refrigerant and secondary-side refrigerant in a case where the intermediate heat exchanger 107ba in the air-conditioning apparatus according to
Embodiment 4 of the present invention functions as a radiator. - FIG. 20
- illustrates a configuration in which intermediate heat exchangers 107aa and 107ba each include three heat transfer units.
- FIG. 21
- is a schematic diagram of an air-conditioning apparatus according to
Embodiment 5 of the present invention. - FIG. 22
- illustrates an installation example of an air-conditioning apparatus according to
Embodiment 6 of the present invention. -
FIG. 1 is a schematic diagram of an air-conditioning apparatus according toEmbodiment 1 of the present invention, illustrating the flow of a refrigerant in the cooling operation.FIG. 2 is a schematic diagram of the air-conditioning apparatus, illustrating the flow of refrigerant in the heating operation. Of the arrows inFIGs. 1 and 2 , arrows indicated by thick lines indicate the flow of a primary-side refrigerant, and arrows indicated by narrow lines indicate the flow of a secondary-side refrigerant. - The air-conditioning apparatus according to
Embodiment 1 includes two refrigerant circuits, a primary-side refrigerant circuit, and a secondary-side refrigerant circuit. - As the primary-side refrigerant that flows through the primary-side refrigerant circuit of these refrigerant circuits, for example, a fluorocarbon refrigerant such as R410A, a hydrocarbon refrigerant such as propane, a natural refrigerant such as carbon dioxide, or the like is used. It is also possible to use an azeotropic refrigerant mixture such as R410A, or a zeotropic refrigerant mixture such as R407C, R32, and R134a, or R32 and R1234yf.
- As the secondary-side refrigerant that flows through the secondary-side refrigerant circuit, for example, brine, water, a liquid mixture of brine and water, a liquid mixture of water and an additive having an anti-corrosion effect, or the like is used.
- The primary-side refrigerant circuit includes at least a compressor 3, an
outdoor heat exchanger 4, anexpansion mechanism 5, a four-way valve 6, and anintermediate heat exchanger 7. The primary-side refrigerant circuit is configured by connecting the compressor 3, the four-way valve 6, theoutdoor heat exchanger 4, theexpansion mechanism 5, theintermediate heat exchanger 7, the four-way valve 6, and the compressor 3 in this order by refrigerant pipes. - The secondary-side refrigerant circuit includes at least the
intermediate heat exchanger 7, anindoor heat exchanger 8, a pump 9, andvalves 10a to 10d. The secondary-side refrigerant circuit is configured by connecting the pump 9, theindoor heat exchanger 8, thevalve 10b, theintermediate heat exchanger 7, thevalve 10a, and the pump 9 in this order by refrigerant pipes. - In the secondary-side refrigerant circuit, a
branch part 30a on the refrigerant pipe connecting theindoor heat exchanger 8 and thevalve 10b is connected to abranch part 30b on the refrigerant pipe connecting thevalve 10a and theintermediate heat exchanger 7, by a refrigerant pipe via thevalve 10d. - Also, in the secondary-side refrigerant circuit, a branch part 30c on the refrigerant pipe connecting the
intermediate heat exchanger 7 and thevalve 10b is connected to abranch part 30d on the refrigerant pipe connecting the pump 9 and thevalve 10a, by a refrigerant pipe via thevalve 10c. - The
intermediate heat exchanger 7 includes at leastheat transfer units check valves 11a to 11c, andcheck valves 12a to 12c. As will be described later, each of theheat transfer units - In the
heat transfer unit 7b, one refrigerant outlet/inlet of the refrigerant flow path through which the primary-side refrigerant flows is connected to the four-way valve 6 by a refrigerant pipe. The other refrigerant outlet/inlet is connected to theexpansion mechanism 5 by a refrigerant pipe via thecheck valve 11b. - In the
heat transfer unit 7a, one refrigerant outlet/inlet of the refrigerant flow path through which the primary-side refrigerant flows is connected to abranch part 20b on the refrigerant pipe connecting theheat transfer unit 7b and thecheck valve 11b, by a refrigerant pipe. The other refrigerant outlet/inlet is connected to abranch part 20d on the refrigerant pipe connecting theheat transfer unit 7b and the four-way valve 6, by a refrigerant pipe via thecheck valve 11a. - Further, a branch part 20c on the refrigerant pipe connecting the
heat transfer unit 7a and thecheck valve 11a is connected to abranch part 20a on the refrigerant pipe connecting theexpansion mechanism 5 and thecheck valve 11b, by a refrigerant pipe via thecheck valve 11c. - In the
heat transfer unit 7b, one refrigerant outlet/inlet of the refrigerant flow path through which the secondary-side refrigerant flows is connected to thevalve 10a by a refrigerant pipe. The other refrigerant outlet/inlet is connected to thevalve 10b by a refrigerant pipe via thecheck valve 12b. - In the
heat transfer unit 7a, one refrigerant outlet/inlet of the refrigerant flow path through which the secondary-side refrigerant flows is connected to a branch part 31 c on the refrigerant pipe connecting theheat transfer unit 7b and thecheck valve 12b, by a refrigerant pipe. The other refrigerant outlet/inlet is connected to a branch part 31a on the refrigerant pipe connecting theheat transfer unit 7b and thevalve 10a, by a refrigerant pipe via thecheck valve 12a. - Further, a
branch part 31d on the refrigerant pipe connecting thecheck valve 12b and thevalve 10b is connected to abranch part 31 b on the refrigerant pipe connecting theheat transfer unit 7a and thecheck valve 12a, by a refrigerant pipe via thecheck valve 12c. - The compressor 3 sucks the primary-side refrigerant in a gas state, compresses the primary-side refrigerant into a high-temperature, high-pressure state, and discharges the resulting primary-side refrigerant. The compressor 3 may be configured by, for example, an inverter compressor or the like whose capacity can be controlled.
- The
outdoor heat exchanger 4 functions as a radiator in the cooling operation, and functions as an evaporator in the heating operation. Theoutdoor heat exchanger 4 exchanges heat between the outdoor air supplied from afan 4a and the primary-side refrigerant. - The
expansion mechanism 5 expands and reduces the pressure of the primary-side refrigerant that has flowed out of theoutdoor heat exchanger 4 in the cooling operation, and the primary-side refrigerant that has flowed out of theintermediate heat exchanger 7 in the heating operation. - The four-
way valve 6 has the function of switching the refrigerant flow path. Specifcally, in the cooling operation, the four-way valve 6 switches the refrigerant flow path so that the primary-side refrigerant discharged from the compressor 3 flows to theoutdoor heat exchanger 4, and that the primary-side refrigerant that has flowed out of theintermediate heat exchanger 7 flows to the compressor 3. In the heating operation, the four-way valve 6 switches the refrigerant flow path so that the primary-side refrigerant discharged from the compressor 3 flows to theintermediate heat exchanger 7, and that the primary-side refrigerant that has flowed out of theoutdoor heat exchanger 4 flows to the compressor 3. - The
heat transfer units heat transfer units - Specifically, each of the
heat transfer units - In a case where a plate heat exchanger is used as each of the
heat transfer units heat transfer units heat transfer units heat transfer units - The
indoor heat exchanger 8 functions as a cooler in the cooling operation, and functions as a radiator in the heating operation. Theindoor heat exchanger 8 exchanges heat between the indoor air supplied from a fan 8a and the secondary-side refrigerant. - The pump 9 causes the secondary-side refrigerant to circuit within the secondary-side refrigerant circuit as the pump 9 is driven.
- The
valves 10a to 10d are opening and closing valves, which conduct the secondary-side refrigerant when open, and shut off the flow of the secondary-side refrigerant when closed. Specifically, thevalves 10a to 10d have the function of switching the outlet/inlet through which the secondary-side refrigerant that has flowed out of theindoor heat exchanger 8 flows into theintermediate heat exchanger 7. - The
check valves 11a to 11c cause the primary-side refrigerant to flow in only one direction. Specifically, thecheck valve 11a causes the primary-side refrigerant to flow only in a direction from the branch part 20c toward thebranch part 20d. Thecheck valve 11b causes the primary-side refrigerant to flow only in a direction from thebranch part 20a toward thebranch part 20b. Thecheck valve 11c causes the primary-side refrigerant to flow only in a direction from the branch part 20c toward thebranch part 20a. - The
check valves 12a to 12c cause the secondary-side refrigerant to flow in only one direction. Specifically, thecheck valve 12a causes the secondary-side refrigerant to flow only in a direction from the branch part 31 a toward thebranch part 31b. Thecheck valve 12b causes the secondary-side refrigerant to flow only in a direction from the branch part 31 c toward thebranch part 31d. Thecheck valve 12c causes the secondary-side refrigerant to flow only in a direction from thebranch part 31d toward thebranch part 31b. - While the
branch parts 20a to 20d, 30a to 30d, and 31a to 31d are provided on refrigerant pipes as illustrated inFIGs. 1 and 2 for the sake of convenience in explaining the refrigerant circuit configuration, this should not be construed restrictively. That is, these branch parts may not necessarily be provided on refrigerant pipes in a clear manner. For example, while thecheck valve 11b and thecheck valve 11c are both connected to theexpansion mechanism 5 via thebranch part 20a, thecheck valve 11b and thecheck valve 11c may be connected to theexpansion mechanism 5 directly without passing through aclear branch part 20a. - This configuration does not alter the function of the refrigerant circuit at all. Furthermore, for example, while the
branch part 30b and the branch part 31 a are configured as separate branch parts for the convenience of explanation of the refrigerant circuit, thebranch part 30b and the branch part 31a may be configured as an integral branch part, and this configuration does not alter the function of the refrigerant circuit at all, either. The same applies to the other branch parts. - As long as the function of the refrigerant circuit (such as the flow directions of the respective refrigerants) illustrated in
FIGs. 1 and 2 remains the same, as mentioned above, it is not necessary to provide clear branch parts, nor is it necessary for the branch parts to be separated as separate components. - The
outdoor heat exchanger 4 and theindoor heat exchanger 8 correspond to the "heat source-side heat exchanger" and the "use-side heat exchanger", respectively, in the invention according to claim 9 of the present invention. The four-way valve 6 and thevalves 10a to 10d correspond to the "first flow switching means" and the "second flow switching means", respectively, in the invention according to claim 9 of the present invention. Thecheck valves 11a to 11c and thecheck valves 12a to 12c each correspond to the "third flow switching means" according to claim 9 of the present invention. - Next, the cooling operation of an air-conditioning apparatus according to
Embodiment 1 will be described with reference toFIG. 1 . - In the primary-side refrigerant circuit, the four-
way valve 6 is switched in advance so that the primary-side refrigerant discharged from the compressor 3 flows to theoutdoor heat exchanger 4, and that the primary-side refrigerant that has flowed out of theintermediate heat exchanger 7 flows to the compressor 3. In the secondary-side refrigerant circuit, thevalve 10a and thevalve 10b are closed, and thevalve 10c and thevalve 10d are open. - First, the flow of the primary-side refrigerant in the primary-side refrigerant circuit will be described. The primary-side refrigerant in a low-temperature, low-pressure gas state is compressed by the compressor 3, and discharged in a high-temperature, high-pressure state. The high-temperature, high-pressure primary-side refrigerant discharged from the compressor 3 flows into the
outdoor heat exchanger 4 via the four-way valve 6. The primary-side refrigerant that has flowed into theoutdoor beat exchanger 4 radiates heat to the outdoor air sent by thefan 4a, and a part or the entire primary-side refrigerant condenses and turns into a two-phase gas-liquid state or liquid state. - The primary-side refrigerant in a two-phase gas-liquid state or liquid state that has flowed out of the
outdoor heat exchanger 4 flows into theexpansion mechanism 5, where the primary-side refrigerant is expanded and reduced in pressure and turns into a two-phase gas-liquid state at low temperature and low pressure. The primary-side refrigerant in a two-phase gas-liquid state at low temperature and low pressure that has flowed out of theexpansion mechanism 5 flows into theintermediate heat exchanger 7. - After the primary-side refrigerant in a two-phase gas-liquid state that has flowed into the
intermediate heat exchanger 7 passes through thebranch part 20a and thecheck valve 11b, the primary-side refrigerant divides into branch flows at thebranch part 20b, and the branch flows flow into theheat transfer unit 7a and theheat transfer unit 7b in parallel, respectively. At this time, at thebranch part 20a, the primary-side refrigerant does not flow in a direction from thebranch part 20a toward the branch part 20c owing to the action of thecheck valve 11c. - The flows of the primary-side refrigerant in a two-phase gas-liquid state that have flowed into the
heat transfer unit 7a and theheat transfer unit 7b absorb heat from the secondary-side refrigerant flowing in counterflow to the primary-side refrigerant, and evaporates and turns into a low-temperature, low-pressure gas state. The primary-side refrigerant in a gas state that has flowed out of theheat transfer unit 7a passes though the branch part 20c and thecheck valve 11a, merges at thebranch part 20d with the primary-side refrigerant in a gas state that has flowed out of theheat transfer unit 7b, and the merged primary-side refrigerant flows out of theintermediate heat exchanger 7. - The primary-side refrigerant in a gas state that has flowed out of the
intermediate heat exchanger 7 is sucked into the compressor 3 via the four-way valve 6, and is compressed again. - Next, the flow of the secondary-side refrigerant in the secondary-side refrigerant circuit will be described. The secondary-side refrigerant sent out by driving of the pump 9 flows into the
indoor heat exchanger 8. The secondary-side refrigerant that has flowed into theindoor heat exchanger 8 cools the indoor air sent by the fan 8a, and flows into theintermediate heat exchanger 7 via thebranch part 30a, thevalve 10d, and thebranch part 30b. - At this time, at the
branch part 30a, the secondary-side refrigerant does not flow in a direction from thebranch part 30a toward the branch part 30c because thevalve 10b is closed. Also, at thebranch part 30b, the secondary-side refrigerant does not flow in a direction from thebranch part 30b toward thebranch part 30d because thevalve 10a is closed. - The secondary-side refrigerant that has flowed into the
intermediate heat exchanger 7 divides into branch flows at the branch part 31a, one of which flows into theheat transfer unit 7b, and the other flows into theheat transfer unit 7a via thecheck valve 12a and thebranch unit 31b. At this time, at thebranch part 31b, the secondary-side refrigerant does not flow in a direction from thebranch part 31b toward thebranch part 31d owing to the action of thecheck valve 12c. - The flows of the secondary-side refrigerant that have flowed into the
heat transfer unit 7a and theheat transfer unit 7b in parallel are cooled by the primary-side refrigerant in a low-temperature state flowing in counterflow to the secondary-side refrigerant, and flow into theheat transfer unit 7a and theheat transfer unit 7b, respectively. The respective flows of the secondary-side refrigerant that have flowed out of theheat transfer unit 7a and theheat transfer unit 7b merge at the branch part 31 c, and the merged secondary-side refrigerant flows out of theintermediate heat exchanger 7 via thecheck valve 12b and thebranch part 31d. - The secondary-side refrigerant that has flowed out of the
intermediate heat exchanger 7 flows into the pump 9 via the branch part 30c, thevalve 10c, and thebranch part 30d, and is sent out again. At this time, at the branch part 30c, the secondary-side refrigerant does not flow in a direction from the branch part 30c toward thebranch part 30a because thevalve 10b is closed. Also, at thebranch part 30d, the secondary-side refrigerant does not flow in a direction from thebranch part 30d toward thebranch part 30b because thevalve 10a is closed. - Next, the heating operation in the air-conditioning apparatus according to
Embodiment 1 will be described with reference toFIG. 2 . - In the primary-side refrigerant circuit, the four-
way valve 6 is switched in advance so that the primary-side refrigerant discharged from the compressor 3 flows to theintermediate heat exchanger 7, and that the primary-side refrigerant that has flowed out of theoutdoor heat exchanger 4 flows to the compressor 3. In the secondary-side refrigerant circuit, thevalve 10a and thevalve 10b are open, and thevalve 10c and thevalve 10d are closed. - First, the flow of the primary-side refrigerant in the primary-side refrigerant circuit will be described. The primary-side refrigerant in a low-temperature, low-pressure gas state is compressed by the compressor 3, and discharged in a high-temperature, high-pressure state. The high-temperature, high-pressure primary-side refrigerant discharged from the compressor 3 flows into the
intermediate heat exchanger 7 via the four-way valve 6. - The primary-side refrigerant that has flowed into the
intermediate heat exchanger 7 flows into theheat transfer unit 7b via thebranch part 20d, and radiates heat to the secondary-side refrigerant flowing in counterflow to the primary-side refrigerant. At this time, at thebranch part 20d, the primary-side refrigerant does not flow in a direction from thebranch part 20d toward the branch part 20c owing to the action of thecheck valve 11a. The primary-side refrigerant that has flowed out of theheat transfer unit 7b flows into theheat transfer unit 7a via thebranch part 20b. - In the
heat transfer unit 7a as well, the primary-side refrigerant radiates heat to the secondary-side refrigerant flowing in counterflow to the primary-side refrigerant. At this time, at thebranch part 20b, the primary-side refrigerant does not flow in a direction from thebranch part 20b toward thebranch part 20a owing to the action of thecheck valve 11b. In this way, unlike the cooling operation described above, the primary-side refrigerant flows through theheat transfer unit 7b and theheat transfer unit 7a in series. - During this process, the primary-side refrigerant radiates heat to the secondary-side refrigerant, and a part or the entire primary-side refrigerant condenses and turns into a two-phase gas-liquid state or liquid state. The primary-side refrigerant in a two-phase gas-liquid state or liquid state that has flowed out of the
beat transfer unit 7a flows out of theintermediate heat exchanger 7 via the branch part 20c, thecheck valve 11c, and thebranch part 20a. - The primary-side refrigerant in a two-phase gas-liquid state or liquid state that has flowed out of the
intermediate heat exchanger 7 flows into theexpansion mechanism 5, where the primary-side refrigerant is expanded and reduced in pressure and turns into a two-phase gas-liquid state at low temperature and low pressure. The primary-side refrigerant in a two-phase gas-liquid state at low temperature and low pressure that has flowed out of theexpansion mechanism 5 flows into theoutdoor heat exchanger 4. - The primary-side refrigerant that has flowed into the
outdoor heat exchanger 4 absorbs heat from the outdoor air sent by thefan 4a, and evaporates and turns into a low-temperature, low-pressure gas state. The primary-side refrigerant in a gas state that has flowed out of theoutdoor heat exchanger 4 is sucked into the compressor 3 via the four-way valve 6, and is compressed again. - Next, the flow of the secondary-side refrigerant in the secondary-side refrigerant circuit will be described. The secondary-side refrigerant sent out by driving of the pump 9 flows into the
indoor heat exchanger 8. The secondary-side refrigerant that has flowed into theindoor heat exchanger 8 heats the indoor air sent by the fan 8a, and flows into theintermediate heat exchanger 7 via thebranch part 30a, thevalve 10b, and the branch part 30c. - At this time, at the
branch part 30a, the secondary-side refrigerant does not flow in a direction from thebranch part 30a toward thebranch part 30b because thevalve 10d is closed. Also, at the branch part 30c, the secondary-side refrigerant does not flow in a direction from the branch part 30c toward thebranch part 30d because thevalve 10c is closed. - The secondary-side refrigerant that has flowed into the
intermediate heat exchanger 7 flows into theheat transfer unit 7a via thebranch part 31d, thecheck valve 12c, and thebranch part 31b, and is heated by the primary-side refrigerant flowing in counterflow to the secondary-side refrigerant. - At this time, at the
branch part 31d, the secondary-side refrigerant does not flow in a direction from thebranch part 31d toward the branch part 31c owing to the action of thecheck valve 12b. Also, at thebranch part 31b, the secondary-side refrigerant does not flow in a direction from thebranch part 31b toward the branch part 31a owing to the action of thecheck valve 12a. The secondary-side refrigerant that has flowed out of theheat transfer unit 7a flows into theheat transfer unit 7b via the branch part 31c, and is heated by the primary-side refrigerant flowing in counterflow to the secondary-side refrigerant. - In this way, unlike the cooling operation described above, the secondary-side refrigerant flows through the
heat transfer unit 7a and theheat transfer unit 7b in series. The secondary-side refrigerant that has flowed out of theheat transfer unit 7b flows out of theintermediate heat exchanger 7 via the branch part 31a. - The secondary-side refrigerant that has flowed out of the
intermediate heat exchanger 7 flows into the pump 9 via thebranch part 30b, thevalve 10a, and thebranch part 30d, and is sent out again. At this time, at thebranch part 30b, the secondary-side refrigerant does not flow in a direction from thebranch part 30b toward thebranch part 30a because thevalve 10d is closed. Also, at thebranch part 30d, the secondary-side refrigerant does not flow in a direction from thebranch part 30d toward the branch part 30c because thevalve 10c is closed. -
FIG. 3 illustrates the temperature relationship between the primary-side refrigerant and the secondary-side refrigerant in theintermediate heat exchanger 7 in the heating operation, in a case where a refrigerant whose discharge pressure is lower than the critical point is used as the primary-side refrigerant in the air-conditioning apparatus according toEmbodiment 1 of the present invention. -
FIG. 4 illustrates the temperature relationship between the primary-side refrigerant and the secondary-side refrigerant in theintermediate heat exchanger 7 in the heating operation, in a case where a refrigerant whose discharge pressure is higher than the critical point is used as the primary-side refrigerant in the air-conditioning apparatus. - Unlike the primary-side refrigerant at a low discharge pressure as illustrated in
FIG. 3 , the primary-side refrigerant at a high discharge pressure as illustrated inFIG. 4 has high discharge temperature, and does not become a two-phase state in theintermediate heat exchanger 7, resulting in large amount of heat exchange with the secondary-side refrigerant. - Therefore, a large target value can be set for the outlet-inlet temperature difference in the
intermediate heat exchanger 7 through which the secondary-side refrigerant flows, or for the outlet-inlet temperature difference in theindoor heat exchanger 8, thereby making it possible to reduce the input to the pump 9. - According to the configuration and the operation mentioned above, in the
intermediate heat exchanger 7, in the cooling operation in which the primary-side refrigerant absorbs heat from the secondary-side refrigerant, the primary-side refrigerant flows through theheat transfer unit 7a and theheat transfer unit 7b in parallel, and in the heating operation in which the primary-side refrigerant radiates heat to the secondary-side refrigerant, the primary-side refrigerant flows through theheat transfer unit 7a and theheat transfer unit 7b in series. - In this regard, generally, with regard to operation efficiency, pressure loss exerts a greater influence than heat transfer capacity in the heat absorption process, whereas heat transfer capacity exerts a greater influence than pressure loss in the heat radiation process.
- Accordingly, in the air-conditioning apparatus according to
Embodiment 1, in the cooling operation, the primary-side refrigerant performs a heat absorption operation in theintermediate heat exchanger 7, and flows through theheat transfer unit 7a and theheat transfer unit 7b in parallel so that the overall cross-sectional area of the flow path becomes large. - Therefore, pressure loss that tends to exert a great influence in the heat absorption process can be reduced, thereby making it possible to reduce the input to the compressor 3. In the heating operation, the primary-side refrigerant performs a heat radiation operation in the
intermediate heat exchanger 7, and flows through theheat transfer unit 7a and theheat transfer unit 7b in series so that the overall cross-sectional area of the flow path becomes small. Thus, flow velocity increases, thereby making it possible to promote heat transfer. Therefore, highly efficient operation is possible in both the cooling operation and the heating operation. - As illustrated in
FIGs. 1 and 2 , theheat transfer unit 7a exists in which the flow directions of both the primary-side refrigerant and the secondary-side refrigerant do not change even when the overall cross-sectional area of the flow path in theintermediate heat exchanger 7 changes as cooling and the heating operations are switched. Consequently, it is possible to take measures such as optimization of refrigerant distribution. - In the cooling operation and the heating operation, even when the flow direction of the secondary-side refrigerant is switched, the secondary-side refrigerant flows through the
indoor heat exchanger 8 only in one direction, and in either case, heat exchange with the indoor air is performed in the same manner, resulting in high heat exchange efficiency. - In a case where a refrigerant whose discharge pressure is higher than the critical point is used as the primary-side refrigerant, in the heating operation, an effect due to lowering of the outlet temperature of the primary-side refrigerant in the
intermediate heat exchanger 7 can be expected. In this case, the outlet-inlet temperature difference of the secondary-side refrigerant can be made large, and the flow rate of the secondary-side refrigerant can be reduced, thereby making it possible to reduce the input to the pump 9. - In the air-conditioning apparatus illustrated in
FIGs. 1 and 2 , use of thecheck valves 11a to 11c and 12a to 12c makes it unnecessary to perform operations other than operations of the four-way valve 6 andvalves 10a to 10d, for switching of the overall cross-sectional area of the flow path in theintermediate heat exchanger 7 due to switching of cooling and the heating operations. Consequently, in the vicinity of theintermediate heat exchanger 7, problems such as leakage of refrigerant from valves can be prevented, thereby enabling safe operation. - While the air-conditioning apparatus illustrated in
FIGs. 1 and 2 is configured so that theintermediate heat exchanger 7 includes two heat transfer units such as theheat transfer unit 7a and theheat transfer unit 7b, this should not be construed restrictively. Theintermediate heat exchanger 7 may include three or more heat transfer units. As an example in this case,FIG. 5 illustrates the flow of refrigerant in the cooling operation in a case where theintermediate heat exchanger 7 includes three heat transfer units (heat transfer units 7a to 7c), andFIG. 6 illustrates the flow of refrigerant in the heating operation in the case of the same configuration. - In a case where the number of heat transfer units is an even number, the resulting configuration is the same as the configuration illustrated in
FIG. 1 and FIG. 2 . That is, letting 2n (n is a natural number not smaller than 1) represent the number of heat transfer units, the number of check valves belonging to the primary-side refrigerant circuit within the intermediate heat exchanger 7 (thecheck valves 11a to 11c inFIGs. 1 and 2 ), and the number of check valves belonging to the secondary-side refrigerant circuit (thecheck valves 12a to 12c inFIGs. 1 and 2 ) are each expressed as (2n+1). - In a case where the number of heat transfer units is an odd number, the resulting configuration is the same as the configuration illustrated in
FIG. 5 and FIG. 6 . That is, letting (2n+1) represent the number of heat transfer units, the number of check valves belonging to the primary-side refrigerant circuit within the intermediate heat exchanger 7 (thecheck valves FIGs. 5 and 6 ), and the number of check valves belonging to the secondary-side refrigerant circuit (thecheck valves FIGs. 5 and 6 ) are each expressed as 2n. Therefore, the number of check valves to be installed relative to the number of heat transfer units can be reduced in the case where the number of heat transfer units is an odd number. - In a case where the number of heat transfer units in the
intermediate heat exchanger 7 is an even number, the number of the above-mentioned heat transfer units in which the flow directions of both the primary-side refrigerant and the secondary-side refrigerant do not change equals 50 % of the total number of heat transfer units. In a case where the number of heat transfer units in theintermediate heat exchanger 7 is an odd number, provided that the number is three, the number of heat transfer units in which both of the flow directions do not change equals 33.3 % of the total number of heat transfer units and its ratio becomes the lowest. - That is, in the case where the number of heat transfer units is an odd number, when the number of heat transfer units is larger than three, and as the number of heat transfer units becomes larger, the ratio of the number of heat transfer units in which both of the flow directions do not change to the total number of heat transfer units becomes larger.
- The
check valves 11a to 11c and 12a to 12c within theintermediate heat exchanger 7 in the air-conditioning apparatus illustrated inFIGs. 1, 2 ,5, and 6 may be valves that can be opened and closed. In this case, for example, in a case where there are two heat transfer units as illustrated inFIGs. 1 and 2 , in the cooling operation, the valves corresponding to thecheck valves check valves - The pump 9 may be a pump whose flow rate can be controlled. In this case, the target value of the outlet-inlet temperature difference of the secondary-side refrigerant in the
intermediate heat exchanger 7, or the outlet-inlet temperature difference of the secondary-side refrigerant in theindoor heat exchanger 8 can be made larger in the heating operation than in the cooling operation, thereby enabling an appropriate operation in both the cooling operation and the heating operation. - As for the four
valves 10a to 10d used to switch the direction of the secondary-side refrigerant flowing into theintermediate heat exchanger 7, as another means, two three-way valves or one four-way valve may be used to form a circuit for switching the flow path direction. In this case, it is possible to reduce the number of components. - While one indoor unit having the
indoor heat exchanger 8 is illustrated as an indoor unit as inFIG. 1 or the like, this should not be construed restrictively. The number of indoor units may be two or more. -
FIG. 7 is a schematic diagram of an air-conditioning apparatus according to Embodiment 2 of the present invention. - The air-conditioning apparatus according to Embodiment 2 allows each individual indoor unit to freely select a cooling operation or the heating operation as an operation mode, by use of a primary-side refrigerant circuit through which the primary-side refrigerant flows and a secondary-side refrigerant circuit through which the secondary-side refrigerant flows.
- As illustrated in
FIG. 7 , as inEmbodiment 1, the air-conditioning apparatus according to Embodiment 2 includes two refrigerant circuits, a primary-side refrigerant circuit, and a secondary-side refrigerant circuit. As the primary-side refrigerant that flows through the primary-side refrigerant circuit of these refrigerant circuits, for example, a fluorocarbon refrigerant such as R410A, a hydrocarbon refrigerant such as propane, a natural refrigerant such as carbon dioxide, or the like is used. - It is also possible to use an azeotropic refrigerant mixture such as R410A, or a zeotropic refrigerant mixture such as R407C, R32, and R134a, or R32 and R1234yf. As the secondary-side refrigerant that flows through the secondary-side refrigerant circuit, for example, brine, water, a liquid mixture of brine and water, a liquid mixture of water and an additive having an anti-corrosion effect, or the like is used. Use of these kinds of secondary-side refrigerant contributes to improvement of safety because even if the secondary-side refrigerant leaks to the indoor space via an indoor unit C described later, a highly safe refrigerant is used as the secondary-side refrigerant.
- The primary-side refrigerant circuit includes at least a
compressor 103, anoutdoor heat exchanger 104,expansion mechanisms way valve 106,intermediate heat exchangers valves 111a to 111e. Roughly speaking, the primary-side refrigerant circuit is configured by connecting thecompressor 103, the four-way valve 106, theoutdoor heat exchanger 104, theexpansion mechanisms intermediate heat exchangers way valve 106, and thecompressor 103 in this order by refrigerant pipes. - The secondary-side refrigerant circuit includes at least the
intermediate heat exchangers FIG. 7 illustrates a case where n = 3.),pumps valves 110a to 110h and 112na to 112nd (n in this case is the same as mentioned above). Roughly speaking, the secondary-side refrigerant circuit is configured by connecting thepumps intermediate heat exchangers pumps - While the number of indoor heat exchangers is three (n = 3) in Embodiment 2, the number may be two, or may be four or more.
- That is, in the air-conditioning apparatus according to Embodiment 2, the primary-side refrigerant that circulates through the primary-side refrigerant circuit, and the secondary-side refrigerant that circulates through the secondary-side refrigerant circuit exchange heat in the
intermediate heat exchangers - While the circuit configuration of each of the primary-side refrigerant circuit and the secondary-side refrigerant circuit mentioned above is a configuration based on a refrigerant circuit through which the same kind of refrigerant flows, as illustrated in
FIG. 7 , when considered on a unit basis, the air-conditioning apparatus according to Embodiment 2 includes an outdoor unit A that is a heat source unit, a plurality of indoor units C1 to C3 (hereinafter, simply referred to as indoor units C when no distinction is made between individual indoor units), and a relay unit B that is interposed between the outdoor unit A and the indoor units C1 to C3. The cooling energy or heating energy generated in the outdoor unit A is transmitted to the indoor units C via the relay unit B. - The outdoor unit A is usually installed in an outdoor space such as the rooftop of a building. The outdoor unit A supplies cooling energy or heating energy to the indoor units C via the relay unit B. The outdoor unit A includes the
compressor 103, theoutdoor heat exchanger 104, and the four-way valve 106. - The
compressor 103 sucks the primary-side refrigerant in a gas state, compresses the primary-side refrigerant into a high-temperature, high-pressure state, and discharges the resulting primary-side refrigerant. Thecompressor 103 may be configured by, for example, an inverter compressor or the like whose capacity can be controlled. - The
outdoor heat exchanger 104 functions as a radiator in the cooling operation, and functions as an evaporator in the heating operation. Theoutdoor heat exchanger 104 exchanges heat between the outdoor air supplied from a fan and the primary-side refrigerant. - The four-
way valve 106 switches between the flow of the primary-side refrigerant in the cooling operation (the cooling only operation mode and the cooling main operation mode described later), and the flow of the primary-side refrigerant in the heating operation (the heating only operation mode and the heating main operation mode described later). Specifically, in the cooling operation, the four-way valve 106 switches the refrigerant flow path so that the primary-side refrigerant discharged from thecompressor 103 flows to theoutdoor heat exchanger 104, and that the primary-side refrigerant that has flowed out of the relay unit B flows to thecompressor 103. - In the heating operation, the four-
way valve 106 switches the refrigerant flow path so that the primary-side refrigerant discharged from thecompressor 103 flows to the relay unit B, and that the primary-side refrigerant that has flowed out of theoutdoor heat exchanger 104 flows to thecompressor 103. - The relay unit B is installed at, for example, a position different from the outdoor space and the indoor space, as a separate casing from the outdoor unit A and the indoor units C. The relay unit B serves as a relay connecting the outdoor unit A and the indoor units C by refrigerant pipes. The relay unit B includes the
intermediate heat exchangers expansion mechanisms pumps valves 110a to 110h, 111a to 111e, and 112na to 112nd. - The
intermediate heat exchangers intermediate heat exchangers intermediate heat exchangers - Of these, the
intermediate heat exchanger 107a is provided between theexpansion mechanism 105a and thevalve 111c in the primary-side refrigerant circuit, and is provided between thevalve 110a and thevalve 110b in the secondary-side refrigerant circuit. Theintermediate heat exchanger 107b is provided between theexpansion mechanism 105b and thevalve 111 d in the primary-side refrigerant circuit, and is provided between thevalve 110e and thevalve 110f in the secondary-side refrigerant circuit. - In a case where a plate heat exchanger is used as each of the
intermediate heat exchangers intermediate heat exchangers intermediate heat exchangers intermediate heat exchangers - The
expansion mechanisms expansion mechanism 105a is provided between theintermediate heat exchanger 107a and thevalve 111 e, and theexpansion mechanism 105b is provided between theintermediate heat exchanger 107b and thevalve 111e. Theexpansion mechanisms - The
valves 111a to 111e are each configured by a two-way valve or the like. Thevalves 111a to 111e each open and close a refrigerant pipe in the primary-side refrigerant circuit, and switch the flow path of the primary-side refrigerant flowing into and flowing out of the relay unit B in the primary-side refrigerant circuit. Thevalve 111a is provided in the refrigerant pipe that connects between the refrigerant pipe connecting theintermediate heat exchanger 107a and thevalve 111c, and the refrigerant pipe connecting thevalve 111b and the outdoor heat exchanger 104 (or thevalve 111e). - The
valve 111b is provided in the refrigerant pipe that connects between the refrigerant pipe connecting theintermediate heat exchanger 107b and thevalve 111d, and the refrigerant pipe connecting thevalve 111a and the outdoor heat exchanger 104 (or thevalve 111e). Thevalve 111c is provided in the refrigerant pipe connecting the four-way valve 106 and theintermediate heat exchanger 107a. Thevalve 111d is provided in the refrigerant pipe connecting the four-way valve 106 and theintermediate heat exchanger 107b. Thevalve 111e is provided in the refrigerant pipe connecting theoutdoor heat exchanger 104 and theexpansion mechanism 105a (or theexpansion mechanism 105b). - Each of the
pumps pumps pump 109a divides into branches, which are respectively connected to thevalves - The refrigerant pipe connected to the suction side of the
pump 109a is connected to thevalve 110a. The refrigerant pipe connected to the discharge side of thepump 109b divides into branches, which are respectively connected to thevalves pump 109b is connected to thevalve 110e. - The
valves 110a to 110h are each configured by a two-way valve or the like. In the secondary-side refrigerant circuit, thevalves 110a to 110h each open and close a refrigerant pipe, and switch the flow path of the secondary-side refrigerant sent to each of thepumps valve 110a is provided in the refrigerant pipe connecting thepump 109a and theintermediate heat exchanger 107a. - The refrigerant pipe connected to one side of the
valve 110b is connected to theintermediate heat exchanger 107a, and the refrigerant pipe connected to the other side divides into branches, which are respectively connected to thevalves valve 110c is provided in the refrigerant pipe that connects between the refrigerant pipe connecting thepump 109a and thevalve 110a, and the refrigerant pipe connecting theintermediate heat exchanger 107a and thevalve 110b. - The
valve 110d is provided in the refrigerant pipe that connects between the refrigerant pipe connecting theintermediate heat exchanger 107a and thevalve 110a, and the refrigerant pipe connecting thevalve 110b and each of thevalves valve 110e is provided in the refrigerant pipe connecting thepump 109b and theintermediate heat exchanger 107b. The refrigerant pipe connected to one side of thevalve 110f is connected to theintermediate heat exchanger 107b, and the refrigerant pipe connected to the other side divides into branches, which are respectively connected to thevalves - The
valve 110g is provided in the refrigerant pipe that connects between the refrigerant pipe connecting thepump 109b and thevalve 110e, and the refrigerant pipe connecting theintermediate heat exchanger 107b and thevalve 110f. Thevalve 110h is provided in the refrigerant pipe that connects between the refrigerant pipe connecting theintermediate heat exchanger 107b and thevalve 110e, and the refrigerant pipe connecting thevalve 110f and each of thevalves - The valves 112na to 112nd (n is a natural number not smaller than 2) switch the flow path of the secondary-side refrigerant sent to the indoor heat exchangers 108n of the indoor units C1 to C3. By adjusting the opening degree (opening area) of the valves 112na to 112nd, the flow rate of the secondary-side refrigerant flowing to the indoor heat exchangers 108n can be controlled.
- The indoor units C1 to C3 include
indoor heat exchangers - The indoor heat exchangers 108n (n is a natural number not smaller than 2) function as a radiator in the heating operation and function as an evaporator in the cooling operation. The indoor heat exchangers 108n exchange heat between the indoor air supplied from a fan and the secondary-side refrigerant, and generates the heating air or cooling air to be supplied to the indoor space. The refrigerant pipe connected to one side of the
indoor heat exchanger 1081 divides into branches, which are respectively connected to thevalves - The refrigerant pipe connected to the other side divides into branches, which are respectively connected to the
valves indoor heat exchanger 1082 divides into branches, which are respectively connected to thevalves valves indoor heat exchanger 1083 divides into branches, which are respectively connected to thevalves valves - While the number of indoor units C connected is three in
FIG. 7 , this should not be construed restrictively. The number of indoor units C connected may be other than three. - The
outdoor heat exchanger 104 and the indoor heat exchangers 108n correspond to the "heat source-side heat exchanger" and the "use-side heat exchangers", respectively, in the invention according toclaim 1 of the present invention. The four-way valve 106, thevalves 111a to 111e, thevalves 110a to 110h, and the valves 112na to 112nd correspond to the "first flow switching means", the "second flow switching means", the "third flow switching means", and the "fourth flow switching means", respectively, in the invention according toclaim 1 of the present invention. - Operation modes performed by the air-conditioning apparatus according to Embodiment 2 include a cooling only operation mode in which all of the indoor units C perform a cooling operation, a heating only operation mode in which all of the indoor units C perform a heating operation, a cooling main operation mode which allows a cooling operation or a heating operation to be selected for each individual indoor unit C and in which the cooling load is greater than the heating load, and a heating main operation mode which allows a cooling operation or a heating operation to be selected for each individual indoor unit C and in which the heating load is greater than the cooling load. Hereinafter, the operation modes will be described together with the flows of the primary-side refrigerant and secondary-side refrigerant.
-
FIG. 8 is a refrigerant circuit diagram illustrating the flows of the primary-side refrigerant and secondary-side refrigerant in the cooling only operation mode of the air-conditioning apparatus according to Embodiment 2 of the present invention. InFIG. 8 , pipes indicated by thick lines represent pipes through which the primary-side refrigerant and the secondary-side refrigerant flow. - In
FIG. 8 , the flow direction of the primary-side refrigerant is indicated by solid arrows, and the flow direction of the secondary-side refrigerant is indicated by broken arrows. Hereinafter, the same applies toFIGs. 9 to 11 . Hereinafter, the cooling only operation mode will be described with reference toFIG. 8 . - In the primary-side refrigerant circuit, the four-
way valve 106 is switched in advance so that the primary-side refrigerant discharged from thecompressor 103 flows to theoutdoor heat exchanger 104, and that the primary-side refrigerant that has flowed out of the relay unit B flows to thecompressor 103, and thevalves valves 111c to 111e are open. In the secondary-side refrigerant circuit, thevalves valves - First, the flow of the primary-side refrigerant in the primary-side refrigerant circuit will be described.
- The primary-side refrigerant in a low-temperature, low-pressure gas state is compressed by the
compressor 103, and discharged in a high-temperature, high-pressure state. The primary-side refrigerant flows into theoutdoor heat exchanger 104 via the four-way valve 106, where the primary-side refrigerant radiates heat to the outdoor air, and a part or the entire primary-side refrigerant condenses and turns into a two-phase gas-liquid state or liquid state. The primary-side refrigerant in a two-phase gas-liquid state or liquid state that has flowed out of theoutdoor heat exchanger 104 flows out of the outdoor unit A, and flows into the relay unit B. - After the primary-side refrigerant that has flowed into the relay unit B passes through the
valve 111e, the primary-side refrigerant divides into branch flows. The branch flows flow into theexpansion mechanisms intermediate heat exchangers - The flows of the primary-side refrigerant in a two-phase gas-liquid state that have flowed into the
intermediate heat exchangers - The flows of the primary-side refrigerant that have flowed out of the
intermediate heat exchangers valves - The primary-side refrigerant in a gas state that has flowed into the outdoor unit A is sucked into the
compressor 103 via the four-way valve 106, and is compressed again. - Next, the flow of the secondary-side refrigerant in the secondary-side refrigerant circuit will be described.
- The secondary-side refrigerant at low temperature sent out by driving of the
pump 109a divides into branch flows. The branch flows flow out of the relay unit B after passing through thevalves indoor heat exchanger 1081 of the indoor unit C1, theindoor heat exchanger 1082 of the indoor unit C2, and theindoor heat exchanger 1083 of the indoor unit C3, respectively. The secondary-side refrigerant at low temperature sent out by driving of thepump 109b divides into branch flows. - The branch flows flow out of the relay unit B after passing through the
valves indoor heat exchanger 1081 of the indoor unit C1, theindoor heat exchanger 1082 of the indoor unit C2, and theindoor heat exchanger 1083 of the indoor unit C3, respectively. The flows of the secondary-side refrigerant that have flowed into theindoor heat exchangers - One of the flows of the secondary-side refrigerant which has passed through the
valve 1121c after flowing out of theindoor heat exchanger 1081, flowing into the relay unit B, and dividing into branch flows, one of the flows of the secondary-side refrigerant which has passed through thevalve 1122c after flowing out of theindoor heat exchanger 1082, flowing into the relay unit B, and dividing into branch flows, and one of the flows of the secondary-side refrigerant which has passed through thevalve 1123c after flowing out of theindoor heat exchanger 1083, flowing into the relay unit B, and dividing into branch flows, merge, and the merged secondary-side refrigerant flows into theintermediate heat exchanger 107a via thevalve 110d. - Also, the other flow of the secondary-side refrigerant which has passed through the
valve 1121d after flowing out of theindoor heat exchanger 1081, flowing into the relay unit B, and dividing into branch flows, the other flow of the secondary-side refrigerant which has passed through thevalve 1122d after flowing out of theindoor heat exchanger 1082, flowing into the relay unit B, and dividing into branch flows, and the other flow of the secondary-side refrigerant which has passed through thevalve 1123d after flowing out of theindoor heat exchanger 1083, flowing into the relay unit B, and dividing into branch flows, merge, and the merged secondary-side refrigerant flows into theintermediate heat exchanger 107b via thevalve 110h. - The flows of the secondary-side refrigerant that have flowed into the
intermediate heat exchangers intermediate heat exchangers intermediate heat exchangers pumps valves -
FIG. 9 is a refrigerant circuit diagram illustrating the flows of the primary-side refrigerant and secondary-side refrigerant in the heating only operation mode of the air-conditioning apparatus according to Embodiment 2 of the present invention. Hereinafter, the heating only operation mode will be described with reference toFIG. 9 . - In the primary-side refrigerant circuit, the four-
way valve 106 is switched in advance so that the primary-side refrigerant discharged from thecompressor 103 flows to the relay unit B, and that the primary-side refrigerant that has flowed out of theoutdoor heat exchanger 104 flows to thecompressor 103, and thevalves valves 111c to 111e are open. In the secondary-side refrigerant circuit, thevalves valves - First, the flow of the primary-side refrigerant in the primary-side refrigerant circuit will be described.
- The primary-side refrigerant in a low-temperature, low-pressure gas state is compressed by the
compressor 103, and discharged in a high-temperature, high-pressure state. The primary-side refrigerant flows out of the outdoor unit A via the four-way valve 106, and flows into the relay unit B. - The primary-side refrigerant that has flowed into the relay unit B divides into branch flows, and the branch flows flow into the
intermediate heat exchangers valves intermediate heat exchangers - The flows of the primary-side refrigerant in a two-phase gas-liquid state or liquid state that have flowed out of the
intermediate heat exchangers expansion mechanisms valve 111e, and flows into the outdoor unit A. - The primary-side refrigerant in a two-phase gas-liquid state that have flowed into the outdoor unit A flows into the
outdoor heat exchanger 104, absorbs heat from the outdoor air, and evaporates and turns into a low-temperature, low-pressure gas state. The primary-side refrigerant is sucked into thecompressor 103 via the four-way valve 106, and is compressed again. - Next, the flow of the secondary-side refrigerant in the secondary-side refrigerant circuit will be described.
- The secondary-side refrigerant at high temperature sent out by driving of the
pump 109a divides into branch flows. The branch flows flow out of the relay unit B after passing through thevalves indoor heat exchanger 1081 of the indoor unit C1, theindoor heat exchanger 1082 of the indoor unit C2, and theindoor beat exchanger 1083 of the indoor unit C3, respectively. - The secondary-side refrigerant at high temperature sent out by driving of the
pump 109b divides into branch flows. The branch flows flow out of the relay unit B after passing through thevalves indoor heat exchanger 1081 of the indoor unit C1, theindoor heat exchanger 1082 of the indoor unit C2, and theindoor heat exchanger 1083 of the indoor unit C3, respectively. - The flows of the secondary-side refrigerant that have flowed into the
indoor heat exchangers - One of the flows of the secondary-side refrigerant which has passed through the
valve 1121c after flowing out of theindoor heat exchanger 1081, flowing into the relay unit B, and dividing into branch flows, one of the flows of the secondary-side refrigerant which has passed through thevalve 1122c after flowing out of theindoor heat exchanger 1082, flowing into the relay unit B, and dividing into branch flows, and one of the flows of the secondary-side refrigerant which has passed through thevalve 1123c after flowing out of theindoor heat exchanger 1083, flowing into the relay unit B, and dividing into branch flows, merge, and the merged secondary-side refrigerant flows into theintermediate heat exchanger 107a via thevalve 110b. - Also, the other flow of the secondary-side refrigerant which has passed through the
valve 1121d after flowing out of theindoor heat exchanger 1081, flowing into the relay unit B, and dividing into branch flows, the other flow of the secondary-side refrigerant which has passed through thevalve 1122d after flowing out of theindoor heat exchanger 1082, flowing into the relay unit B, and dividing into branch flows, and the other flow of the secondary-side refrigerant which has passed through thevalve 1123d after flowing out of theindoor heat exchanger 1083, flowing into the relay unit B, and dividing into branch flows, merge, and the merged secondary-side refrigerant flows into theintermediate heat exchanger 107b via thevalve 110f. - The flows of the secondary-side refrigerant that have flowed into the
intermediate heat exchangers intermediate heat exchangers intermediate heat exchangers pumps valves -
FIG. 10 is a refrigerant circuit diagram illustrating the flows of the primary-side refrigerant and secondary-side refrigerant in the cooling main operation mode of the air-conditioning apparatus according to Embodiment 2 of the present invention. Hereinafter, the cooling main operation mode will be described with reference toFIG. 10 . - In
FIG. 10 , it is assumed that the indoor unit C1 performs a heating operation, and the indoor units C2 and C3 perform a cooling operation. - In the primary-side refrigerant circuit, the four-
way valve 106 is switched in advance so that the primary-side refrigerant discharged from thecompressor 103 flows to theoutdoor heat exchanger 104, and that the primary-side refrigerant that has flowed out of the relay unit B flows to thecompressor 103, and thevalves valves valves valves valves valves - First, the flow of the primary-side refrigerant in the primary-side refrigerant circuit will be described.
- The primary-side refrigerant in a low-temperature, low-pressure gas state is compressed by the
compressor 103, and discharged in a high-temperature, high-pressure state. The primary-side refrigerant flows into theoutdoor heat exchanger 104 via the four-way valve 106, where the primary-side refrigerant radiates heat to the outdoor air, and a part of the primary-side refrigerant condenses and turns into a two-phase gas-liquid state. The primary-side refrigerant in a two-phase gas-liquid state that has flowed out of theoutdoor heat exchanger 104 flows out of the outdoor unit A, and flows into the relay unit B. - The primary-side refrigerant in a two-phase gas-liquid state that has flowed into the relay unit B flows into the
intermediate heat exchanger 107b via thevalve 111b, and further condenses as the primary-side refrigerant heats the secondary-side refrigerant flowing in counterflow to the primary-side refrigerant. As the primary-side refrigerant that has flowed out of theintermediate heat exchanger 107b passes through theexpansion mechanism 105b and theexpansion mechanism 105a, the primary-side refrigerant is expanded and reduced in pressure, turns into a two-phase gas-liquid state at low temperature and low pressure, and flows into theintermediate heat exchanger 107a. - The primary-side refrigerant in a two-phase gas-liquid state that has flowed into the
intermediate heat exchanger 107a absorbs heat from the secondary-side refrigerant flowing in counterflow to the primary-side refrigerant, and evaporates and turns into a low-temperature, low-pressure gas state. The primary-side refrigerant in a low-temperature, low-pressure gas state that has flowed out of theintermediate heat exchanger 107a flows out of the relay unit B via thevalve 111c, and flows into the outdoor unit A. - The primary-side refrigerant in a gas state that has flowed into the outdoor unit A is sucked into the
compressor 103 via the four-way valve 106, and is compressed again. - Next, the flow of the secondary-side refrigerant in the secondary-side refrigerant circuit will be described.
- The secondary-side refrigerant at low temperature sent out by driving of the
pump 109a divides into branch flows. The branch flows flow out of the relay unit B after passing through thevalves indoor heat exchanger 1082 of the indoor unit C2, and theindoor heat exchanger 1083 of the indoor unit C3, respectively. The flows of the secondary-side refrigerant that have flowed into theindoor heat exchangers - The secondary-side refrigerant that has flowed out of the
indoor heat exchanger 1082, flowed into the relay unit B, and passed through thevalve 1122c, and the secondary-side refrigerant that has flowed out of theindoor heat exchanger 1083, flowed into the relay unit B, and passed through thevalve 1123c merge, and the merged secondary-side refrigerant flows into theintermediate heat exchanger 107a via thevalve 110d. - The secondary-side refrigerant that has flowed into the
intermediate heat exchanger 107a is cooled by the primary-side refrigerant in a low-temperature state flowing in counterflow to the secondary-side refrigerant, and flows out of theintermediate heat exchanger 107a. The secondary-side refrigerant that has flowed out of theintermediate heat exchanger 107a flows into thepump 109a via thevalve 110c, and is sent out again. - The secondary-side refrigerant at high temperature sent out by driving of the
pump 109b flows out of the relay unit B after passing through thevalve 1121b, and flows into theindoor heat exchanger 1081 of the indoor unit C1. The secondary-side refrigerant that has flowed into theindoor heat exchanger 1081 heats the indoor air and turn into a low-temperature state, flow out of the indoor unit C1, and flows into the relay unit B. - The secondary-side refrigerant that has flowed out of the
indoor heat exchanger 1081, flowed into the relay unit B, and passed through thevalve 1121 d flows into theintermediate heat exchanger 107b via thevalve 110f. The secondary-side refrigerant that has flowed into theintermediate heat exchanger 107b is heated by the primary-side refrigerant in a high-temperature state flowing in counterflow to the secondary-side refrigerant, and flows out of theintermediate heat exchanger 107b. The secondary-side refrigerant that has flowed out of theintermediate heat exchanger 107b flows into thepump 109b via thevalve 110e, and is sent out again. -
FIG. 11 is a refrigerant circuit diagram illustrating the flows of the primary-side refrigerant and secondary-side refrigerant in the heating main operation mode of the air-conditioning apparatus according to Embodiment 2 of the present invention. Hereinafter, the heating main operation mode will be described with reference toFIG. 11 . InFIG. 11 , it is assumed that the indoor units C1 and C2 perform a heating operation, and the indoor unit C3 performs a cooling operation. - In the primary-side refrigerant circuit, the four-
way valve 106 is switched in advance so that the primary-side refrigerant discharged from thecompressor 103 flows to the relay unit B, and that the primary-side refrigerant that has flowed out of theoutdoor heat exchanger 104 flows to thecompressor 103, and thevalves valves valves valves 110c to 110f are open. Further, thevalves valves - First, the flow of the primary-side refrigerant in the primary-side refrigerant circuit will be described.
- The primary-side refrigerant in a low-temperature, low-pressure gas state is compressed by the
compressor 103, and discharged in a high-temperature, high-pressure state. The primary-side refrigerant flows out of the outdoor unit A via the four-way valve 106, and flows into the relay unit B. - The primary-side refrigerant in a high-temperature, high-pressure state that has flowed into the relay unit B flows into the
intermediate heat exchanger 107b via thevalve 111d, radiates heat to the secondary-side refrigerant flowing in counterflow to the primary-side refrigerant, and a part or the entire primary-side refrigerant condenses and turns into a two-phase gas-liquid state or liquid state. - As the primary-side refrigerant that has flowed out of the
intermediate heat exchanger 107b passes through theexpansion mechanism 105b and theexpansion mechanism 105a, the primary-side refrigerant is expanded and reduced in pressure, turns into a two-phase gas-liquid state at low temperature and low pressure, and flows into theintermediate heat exchanger 107a. - The primary-side refrigerant in a two-phase gas-liquid state that has flowed into the
intermediate heat exchanger 107a absorbs heat from the secondary-side refrigerant flowing in counterflow to the primary-side refrigerant, and partially evaporates. The primary-side refrigerant that has flowed out of theintermediate heat exchanger 107a flows out of the relay unit B via thevalve 111a, and flows into the outdoor unit A. - The primary-side refrigerant that has flowed into the outdoor unit A flows into the
outdoor heat exchanger 104, absorbs heat from the indoor air, and evaporates and turns into a low-temperature, low-pressure gas state. The primary-side refrigerant is sucked into thecompressor 103 via the four-way valve 106, and is compressed again. - Next, the flow of the secondary-side refrigerant in the secondary-side refrigerant circuit will be described.
- The secondary-side refrigerant at low temperature sent out by driving of the
pump 109a flows out of the relay unit B after passing through thevalve 1123a, and flows into theindoor heat exchanger 1083 of the indoor unit C3. The secondary-side refrigerant that has flowed into theindoor heat exchanger 1083 cools the indoor air and turn into a high-temperature state, flows out of the indoor unit C3, and flows into the relay unit B. - The secondary-side refrigerant that has flowed out of the
indoor heat exchanger 1083, flowed into the relay unit B, and passed through thevalve 1123c flows into theintermediate heat exchanger 107a via thevalve 110d. The secondary-side refrigerant that has flowed into theintermediate heat exchanger 107a is cooled by the primary-side refrigerant in a low-temperature state flowing in counterflow to the secondary-side refrigerant, and flows out of theintermediate heat exchanger 107a. The secondary-side refrigerant that has flowed out of theintermediate heat exchanger 107a flows into thepump 109a via thevalve 110a, and is sent out again. - The secondary-side refrigerant at high temperature sent out by driving of the
pump 109b divides into branch flows. The branch flows flow out of the relay unit B after passing through thevalves indoor heat exchanger 1081 of the indoor unit C1, and theindoor heat exchanger 1082 of the indoor unit C2, respectively. The flows of the secondary-side refrigerant that have flowed into theindoor heat exchangers - The secondary-side refrigerant that has flowed out of the
indoor heat exchanger 1081, flowed into the relay unit B, and passed through thevalve 1121 d, and the secondary-side refrigerant that has flowed out of theindoor heat exchanger 1082, flowed into the relay unit B, and passed through thevalve 1122d merge, and the merged secondary-side refrigerant flows into theintermediate heat exchanger 107b via thevalve 110f. - The secondary-side refrigerant that has flowed into the
intermediate heat exchanger 107b is heated by the primary-side refrigerant in a high-temperature state flowing in counterflow to the secondary-side refrigerant, and flows out of theintermediate heat exchanger 107b. The secondary-side refrigerant that has flowed out of theintermediate heat exchanger 107b flows into thepump 109b via thevalve 110e, and is sent out again. - According to the configuration and the operation mentioned above, in any operation mode, the primary-side refrigerant and the secondary-side refrigerant flow in counterflow directions in both of the
intermediate heat exchangers pumps - In a case where a refrigerant whose discharge pressure is higher than the critical point is used as the primary-side refrigerant, the discharge temperature of the refrigerant is higher than that of a refrigerant whose discharge pressure is lower than the critical point, and the refrigerant does not become a two-phase gas-liquid state. Therefore, the target value of the outlet-inlet temperature difference of the secondary-side refrigerant within the intermediate heat exchanger can be set to a large value, thereby making it possible to reduce the input to the pump.
- In a case where a zeotropic refrigerant mixture is used as the primary-side refrigerant, because a zeotropic refrigerant mixture undergoes a temperature change when its phase changes, as compared with a case where a single refrigerant or azeotropic refrigerant mixture that does not undergo a temperature change when its phase changes is used, heat exchange can be performed efficiently when the primary-side refrigerant and the secondary-side refrigerant are made to flow in counterflow directions in the intermediate heat exchanger.
- As for the four
valves 110a to 110d used to switch the direction of the secondary-side refrigerant flowing into theintermediate heat exchanger 107a, and the fourvalves 110e to 110h used to switch the direction of the secondary-side refrigerant flowing into theintermediate heat exchanger 107b, as another means, two three-way valves or one four-way valve may be used to form a circuit for switching the flow path direction. In this case, it is possible to reduce the number of components. - As for the valves 112na and 112nb used to switch the direction of the secondary-side refrigerant flowing into the indoor heat exchangers 108n as well, as another means, these valves may be configured as one three-way valve, in which case it is possible to reduce the number of components. The same applies to the valves 112nc and 112nd used to switch the direction of the secondary-side refrigerant that has flowed out of the indoor heat exchangers 108n.
- An air-conditioning apparatus according to Embodiment 3 will be described while mainly focusing on differences from the air-conditioning apparatus according to Embodiment 2.
-
FIG. 12 is a schematic diagram of an air-conditioning apparatus according to Embodiment 3 of the present invention. - As illustrated in
FIG. 12 , the outdoor unit A includes thecompressor 103, theoutdoor heat exchanger 104, the four-way valve 106, and aflow switching unit 141 includingcheck valves 113a to 113d. - As will be described later, the
flow switching unit 141 including thecheck valves 113a to 113d has the function of causing the primary-side refrigerant flowing within the refrigerant pipes connecting the outdoor unit A and the relay unit B to flow in a certain direction. Thecheck valve 113a is provided in the refrigerant pipe connecting the four-way valve 106 and each of thevalves valves way valve 106. - The
check valve 113b is provided in the refrigerant pipe connecting theoutdoor heat exchanger 104 and thevalve 111f described later, and causes the primary-side refrigerant to flow only in a direction from theoutdoor heat exchanger 104 toward thevalve 111f. Thecheck valve 113c is provided in the refrigerant pipe that connects between the refrigerant pipe connecting the four-way valve 106 and thecheck valve 113a, and the refrigerant pipe connecting thecheck valve 113b and thevalve 111f, and causes the primary-side refrigerant to flow only in a direction from the refrigerant pipe connecting the four-way valve 106 and thecheck valve 113a toward the refrigerant pipe connecting thecheck valve 113b and thevalve 111f. - The
check valve 113d is provided in the refrigerant pipe that connects between the refrigerant pipe connecting thecheck valve 113a and each of thevalves indoor heat exchanger 104 and thecheck valve 113b, and causes the primary-side refrigerant to flow only in a direction from the refrigerant pipe connecting thecheck valve 113a and each of thevalves indoor heat exchanger 104 and thecheck valve 113b. - The relay unit B includes the
intermediate heat exchangers expansion mechanisms pumps valves 110a to 1110h, 111a to 111f, and 112na to 112nd, and abypass pipe 142. - The
valve 111f is configured by a two-way valve or the like. Thevalve 111f is provided in the refrigerant pipe between thevalve 111e, and the point where the refrigerant pipe into which refrigerant pipes connected to thevalves check valve 113b and thevalve 111e. - The
bypass pipe 142 is a refrigerant pipe that connects between the refrigerant pipe connecting thecheck valve 113a and each of thevalves valve 111e and thevalve 111f. - Hereinafter, operation modes will be described together with the flow of the primary-side refrigerant.
- The flow of the secondary-side refrigerant is the same as that in
Embodiment 1. -
FIG. 13 is a refrigerant circuit diagram illustrating the flows of the primary-side refrigerant and secondary-side refrigerant in the cooling only operation mode of the air-conditioning apparatus according to Embodiment 3 of the present invention. InFIG. 13 , pipes indicated by thick lines represent pipes through which the primary-side refrigerant and the secondary-side refrigerant flow. InFIG. 13 , the flow direction of the primary-side refrigerant is indicated by solid arrows, and the flow direction of the secondary-side refrigerant is indicated by broken arrows. Hereinafter, the same applies toFIGs. 14 to 16 . Hereinafter, the cooling only operation mode will be described with reference toFIG. 13 . - In the primary-side refrigerant circuit, the four-
way valve 106 is switched in advance so that the primary-side refrigerant discharged from thecompressor 103 flows to theoutdoor heat exchanger 104, and that the primary-side refrigerant that has flowed out of the relay unit B flows to thecompressor 103, and thevalves valves 111c to 111f are open. In the secondary-side refrigerant circuit, thevalves valves - As described above, only the flow of the primary-side refrigerant in the primary-side refrigerant circuit will be described.
- The primary-side refrigerant in a low-temperature, low-pressure gas state is compressed by the
compressor 103, and discharged in a high-temperature, high-pressure state. The primary-side refrigerant flows into theoutdoor heat exchanger 104 via the four-way valve 106, where the primary-side refrigerant radiates heat to the outdoor air, and a part or the entire primary-side refrigerant condenses and turns into a two-phase gas-liquid state or liquid state. The primary-side refrigerant in a two-phase gas-liquid state or liquid state that has flowed out of theoutdoor heat exchanger 104 flows out of the outdoor unit A via thecheck valve 113b, and flows into the relay unit B. - After the primary-side refrigerant that has flowed into the relay unit B passes through the
valves 111f and thevalve 111e, the primary-side refrigerant divides into branch flows. The branch flows flow into theexpansion mechanisms intermediate heat exchangers - The flows of the primary-side refrigerant in a two-phase gas-liquid state that have flowed into the
intermediate heat exchangers intermediate heat exchangers valves - The primary-side refrigerant in a gas state that has flowed into the outdoor unit A is sucked into the
compressor 103 via thecheck valve 113a and the four-way valve 106, and is compressed again. -
FIG. 14 is a refrigerant circuit diagram illustrating the flows of the primary-side refrigerant and secondary-side refrigerant in the heating only operation mode of the air-conditioning apparatus according to Embodiment 3 of the present invention. Hereinafter, the heating only operation mode will be described with reference toFIG. 14 . - In the primary-side refrigerant circuit, the four-
way valve 106 is switched in advance so that the primary-side refrigerant discharged from thecompressor 103 flows to the relay unit B, and that the primary-side refrigerant that has flowed out of theoutdoor heat exchanger 104 flows to thecompressor 103, and thevalves valves valves valves - As described above, only the flow of the primary-side refrigerant in the primary-side refrigerant circuit will be described.
- The primary-side refrigerant in a low-temperature, low-pressure gas state is compressed by the
compressor 103, and discharged in a high-temperature, high-pressure state. The primary-side refrigerant flows out of the outdoor unit A via the four-way valve 106 and thecheck valve 113c, and flows into the relay unit B. - The primary-side refrigerant that has flowed into the relay unit B divides into branch flows, and the branch flows flow into the
intermediate heat exchangers valves intermediate heat exchangers - The flows of the primary-side refrigerant in a two-phase gas-liquid state or liquid state that have flowed out of the
intermediate heat exchangers expansion mechanisms valve 111e, and flows out of the relay unit B after flowing through thebypass pipe 142, and flows into the outdoor unit A. - The primary-side refrigerant in a two-phase gas-liquid state that have flowed into the outdoor unit A flows into the
outdoor heat exchanger 104 via thecheck valve 113d, absorbs heat from the outdoor air, and evaporates and turns into a low-temperature, low-pressure gas state. The primary-side refrigerant is sucked into thecompressor 103 via the four-way valve 106, and is compressed again. -
FIG. 15 is a refrigerant circuit diagram illustrating the flows of the primary-side refrigerant and secondary-side refrigerant in the cooling main operation mode of the air-conditioning apparatus according to Embodiment 3 of the present invention. Hereinafter, the cooling main operation mode will be described with reference toFIG. 15 . InFIG. 15 , it is assumed that the indoor unit C1 performs a heating operation, and the indoor units C2 and C3 perform a cooling operation. - In the primary-side refrigerant circuit, the four-
way valve 106 is switched in advance so that the primary-side refrigerant discharged from thecompressor 103 flows to theoutdoor heat exchanger 104, and that the primary-side refrigerant that has flowed out of the relay unit B flows to thecompressor 103, and thevalves valves valves valves valves valves - As described above, only the flow of the primary-side refrigerant in the primary-side refrigerant circuit will be described.
- The primary-side refrigerant in a low-temperature, low-pressure gas state is compressed by the
compressor 103, and discharged in a high-temperature, high-pressure state. The primary-side refrigerant flows into theoutdoor heat exchanger 104 via the four-way valve 106, where the primary-side refrigerant radiates heat to the outdoor air, and a part of the primary-side refrigerant condenses and turns into a two-phase gas-liquid state. The primary-side refrigerant in a two-phase gas-liquid state that has flowed out of theoutdoor heat exchanger 104 flows out of the outdoor unit A via thecheck valve 113b, and flows into the relay unit B. - The primary-side refrigerant in a two-phase gas-liquid state that has flowed into the relay unit B flows into the
intermediate heat exchanger 107b via thevalve 111b, and further condenses as the primary-side refrigerant heats the secondary-side refrigerant flowing in counterflow to the primary-side refrigerant. As the primary-side refrigerant that has flowed out of theintermediate heat exchanger 107b passes through theexpansion mechanism 105b and the expansion mechanism 103a, the primary-side refrigerant is expanded and reduced in pressure, turns into a two-phase gas-liquid state at low temperature and low pressure, and flows into theintermediate heat exchanger 107a. - The primary-side refrigerant in a two-phase gas-liquid state that has flowed into the
intermediate heat exchanger 107a absorbs heat from the secondary-side refrigerant flowing in counterflow to the primary-side refrigerant, and evaporates and turns into a low-temperature, low-pressure gas state. The primary-side refrigerant in a low-temperature, low-pressure gas state that has flowed out of theintermediate heat exchanger 107a flows out of the relay unit B via thevalve 111c, and flows into the outdoor unit A. - The primary-side refrigerant in a gas state that has flowed into the outdoor unit A is sucked into the
compressor 103 via thecheck valve 113a and the four-way valve 106, and is compressed again. -
FIG. 16 is a refrigerant circuit diagram illustrating the flows of the primary-side refrigerant and secondary-side refrigerant in the heating main operation mode of the air-conditioning apparatus according to Embodiment 3 of the present invention. Hereinafter, the heating main operation mode will be described with reference toFIG. 16 . InFIG. 16 , it is assumed that the indoor units C1 and C2 perform a heating operation, and the indoor unit C3 performs a cooling operation. - In the primary-side refrigerant circuit, the four-
way valve 106 is switched in advance so that the primary-side refrigerant discharged from thecompressor 103 flows to the relay unit B, and that the primary-side refrigerant that has flowed out of theoutdoor heat exchanger 104 flows to thecompressor 103, and thevalves valves valves valves 110c to 110f are open. Further, thevalves valves - As described above, only the flow of the primary-side refrigerant in the primary-side refrigerant circuit will be described.
- The primary-side refrigerant in a low-temperature, low-pressure gas state is compressed by the
compressor 103, and discharged in a high-temperature, high-pressure state. The primary-side refrigerant flows out of the outdoor unit A via the four-way valve 106 and thecheck valve 113c, and flows into the relay unit B. - The primary-side refrigerant in a high-temperature, high-pressure state that has flowed into the relay unit B flows into the
intermediate heat exchanger 107b via thevalve 111b, radiates heat to the secondary-side refrigerant flowing in counterflow to the primary-side refrigerant, and a part or the entire primary-side refrigerant condenses and turns into a two-phase gas-liquid state or liquid state. - As the primary-side refrigerant that has flowed out of the
intermediate heat exchanger 107b passes through theexpansion mechanism 105b and theexpansion mechanism 105a, the primary-side refrigerant is expanded and reduced in pressure, turns into a two-phase gas-liquid state at low temperature and low pressure, and flows into theintermediate heat exchanger 107a. - The primary-side refrigerant in a two-phase gas-liquid state that has flowed into the
intermediate heat exchanger 107a absorbs heat from the secondary-side refrigerant flowing in counterflow to the primary-side refrigerant, and partially evaporates. The primary-side refrigerant that has flowed out of theintermediate heat exchanger 107a flows out of the relay unit B via thevalve 111c, and flows into the outdoor unit A. - The primary-side refrigerant that has flowed into the outdoor unit A flows into the
outdoor heat exchanger 104 via thecheck valve 113d, absorbs heat from the indoor air, and evaporates and turns into a low-temperature, low-pressure gas state. The primary-side refrigerant is sucked into thecompressor 103 via the four-way valve 106, and is compressed again. - According to the configuration and the operation mentioned above, irrespective of the operation mode, the primary-side refrigerant flowing through the refrigerant pipes connecting the outdoor unit A and the relay unit B flow in a certain direction, and the refrigerant pipes through which a high-pressure refrigerant and a low-pressure refrigerant flow become fixed. Consequently, of the refrigerant pipes connecting the outdoor unit A and the relay unit B, the wall thickness of the refrigerant pipe through which the low-pressure refrigerant flows can be reduced, thereby enabling cost reduction.
- An air-conditioning apparatus according to
Embodiment 4 will be described while mainly focusing on differences from the air-conditioning apparatus according to Embodiment 2. -
FIG. 17 is a schematic diagram of an air-conditioning apparatus according toEmbodiment 4 of the present invention. - As illustrated in
FIG. 17 , in the air-conditioning apparatus according toEmbodiment 4, theintermediate heat exchangers intermediate heat exchanger 7 in the air-conditioning apparatus according toEmbodiment 1. - First,
heat transfer units check valves 132a to 132c and 133a to 133c in the intermediate heat exchanger 107aa correspond to theheat transfer units check valves 11a to 11c and 12a to 12c in theintermediate heat exchanger 7 inEmbodiment 1, respectively.Heat transfer units check valves 132d to 132f and 133d to 133f in the intermediate heat exchanger 107ba correspond to theheat transfer units check valves 11a to 11c and 12a to 12c in theintermediate heat exchanger 7 inEmbodiment 1, respectively. - The operation of the air-conditioning apparatus according to
Embodiment 4 is the same as that of the air-conditioning apparatus according to Embodiment 2, except for the flow of refrigerant within each of the intermediate heat exchangers 107aa and 107ba. Moreover, provided that the primary-side refrigerant and the secondary-side refrigerant flow out of and flow into the intermediate heat exchanger 107aa and theintermediate heat exchanger 107a in the same direction, the operations in the intermediate heat exchanger 107aa and theintermediate heat exchanger 107a are the same. Accordingly, hereinafter, the operation in theintermediate heat exchanger 107a will be described. - The
check valves 132a to 132f and 133a to 133f correspond to the "fifth flow switching means" in the invention according toclaim 5 of the present invention. -
FIG. 18 illustrates the flows of the primary-side refrigerant and secondary-side refrigerant in a case where the intermediate heat exchanger 107ba in the air-conditioning apparatus according toEmbodiment 4 of the present invention functions as an evaporator. InFIG. 18 , pipes indicated by thick lines represent pipes through which the primary-side refrigerant and the secondary-side refrigerant flow. - In
FIG. 18 , the flow direction of the primary-side refrigerant is indicated by solid arrows, and the flow direction of the secondary-side refrigerant is indicated by broken arrows. Hereinafter, the same applies toFIG. 19 . Hereinafter, the operation in a case where the intermediate heat exchanger 107ba functions as an evaporator will be described with reference toFIG. 18 . - After the primary-side refrigerant in a two-phase gas-liquid state that has flowed into the intermediate heat exchanger 107ba passes through the
check valve 132e, the primary-side refrigerant divides into branch flows, and the branch flows flow into theheat transfer unit 1071b and theheat transfer unit 1072b in parallel, respectively. At this time, the primary-side refrigerant does not flow in a direction toward thecheck valve 132d owing to the action of thecheck valve 132f. - The flows of the primary-side refrigerant in a two-phase gas-liquid state that have flowed into the
heat transfer unit 1071b and theheat transfer unit 1072b absorb heat from the secondary-side refrigerant flowing in counterflow to the primary-side refrigerant, and partially evaporate, or evaporate and turn into a low-temperature, low-pressure gas state. The primary-side refrigerant that has flowed out of theheat transfer unit 1071b passes though thecheck valve 132d, merges with the primary-side refrigerant that has flowed out of theheat transfer unit 1072b, and flows out of the intermediate heat exchanger 107ba. - The secondary-side refrigerant that has flowed into the intermediate heat exchanger 107ba divides into branch flows, one of which flows into the
heat transfer unit 1072b, and the other flows into theheat transfer unit 1071b via thecheck valve 133d. At this time, the secondary-side refrigerant does not flow in a direction toward the outlet of the secondary-side refrigerant in the intermediate heat exchanger 107ba owing to the action of thecheck valve 133f. - The flows of the secondary-side refrigerant that have flowed into the
heat transfer unit 1071b and theheat transfer unit 1072b in parallel are cooled by the primary-side refrigerant in a low-temperature state flowing in counterflow to the secondary-side refrigerant, and flow out of theheat transfer unit 1071b and theheat transfer unit 1072b, respectively. The flows of the secondary-side refrigerant that have respectively flowed out of theheat transfer unit 1071b and theheat transfer unit 1072b merge, and the merged secondary-side refrigerant flows out of the intermediate heat exchanger 107ba via thecheck valve 133e. -
FIG. 19 illustrates the flows of the primary-side refrigerant and secondary-side refrigerant in a case where the intermediate heat exchanger 107ba in the air-conditioning apparatus according toEmbodiment 4 of the present invention functions as a radiator. InFIG. 19 , pipes indicated by thick lines represent pipes through which the primary-side refrigerant and the secondary-side refrigerant flow. - In
FIG. 19 , the flow direction of the primary-side refrigerant is indicated by solid arrows, and the flow direction of the secondary-side refrigerant is indicated by broken arrows. Hereinafter, the operation in a case where the intermediate heat exchanger 107ba functions as a radiator will be described with reference toFIG. 19 . - The primary-side refrigerant that has flowed into the intermediate heat exchanger 107ba flows into the
heat transfer unit 1072b, and radiates heat to the secondary-side refrigerant flowing in counterflow to the primary-side refrigerant. At this time, the primary-side refrigerant does not flow in a direction toward theheat transfer unit 1071b and thecheck valve 132f owing to the action of thecheck valve 132d. The primary-side refrigerant that has flowed out of theheat transfer unit 1072b flows into theheat transfer unit 1071b. - In the
heat transfer unit 1071b as well, the primary-side refrigerant radiates heat to the secondary-side refrigerant flowing in counterflow to the primary-side refrigerant. At this time, the primary-side refrigerant does not flow in a direction toward the outlet of the primary-side refrigerant in the intermediate heat exchanger 107ba owing to the action of thecheck valve 132e. - In this way, the primary-side refrigerant flows through the
heat transfer unit 1072b and theheat transfer unit 1071b in series, and during this process, the primary-side refrigerant radiates heat to the secondary-side refrigerant, and a part or the entire primary-side refrigerant condenses and turns into a two-phase gas-liquid state or liquid state. The primary-side refrigerant in a two-phase gas-liquid state or liquid state that has flowed out of theheat transfer unit 1071b flows out of theintermediate heat exchanger 107a via thecheck valve 132f. - The secondary-side refrigerant that has flowed into the intermediate heat exchanger 107ba flows into the
heat transfer unit 1071b via thecheck valve 133f, and is heated by the primary-side refrigerant flowing in counterflow to the secondary-side refrigerant. At this time, the secondary-side refrigerant does not flow in a direction toward theheat transfer unit 1072b owing to the action of thecheck valve 133e. The secondary-side refrigerant does not flow in a direction toward the outlet of the secondary-side refrigerant in the intermediate heat exchanger 107ba, either, owing to the action of thecheck valve 133d. - The secondary-side refrigerant that has flowed out of the
heat transfer unit 1071b flows into theheat transfer unit 1072b, and is heated by the primary-side refrigerant flowing in counterflow to the secondary-side refrigerant. In this way, the secondary-side refrigerant flows through theheat transfer unit 1071b and theheat transfer unit 1072b in series. The secondary-side refrigerant that has flowed out of theheat transfer unit 1072b flows out of the intermediate heat exchanger 107ba. - In the cooling only operation mode, the intermediate heat exchangers 107aa and 107a both act as the evaporator described above with reference to
FIG. 18 , and in the heating only operation mode, the intermediate heat exchangers 107aa and 107ba both act as the radiator described above with reference toFIG. 19 . In both the cooling main operation mode and the heating main operation mode, the intermediate heat exchanger 107aa acts as the evaporator described above with reference toFIG. 18 , and theintermediate heat exchanger 107a acts as the radiator described above with reference toFIG. 19 . - According to the configuration and the operation mentioned above, in a case where each of the intermediate heat exchangers 107aa and 107a functions as an evaporator where the primary-side refrigerant absorbs heat from the secondary-side refrigerant, the primary-side refrigerant flows through the
heat transfer unit 1071a (1071b) and theheat transfer unit 1072a (1072b) in parallel, and in a case where each of the intermediate heat exchangers 107aa and 107a functions as a radiator where the primary-side refrigerant radiates heat to the secondary-side refrigerant, the primary-side refrigerant flows through theheat transfer unit 1071a (1071b) and theheat transfer unit 1072a (1072b) in series. In this regard, as described above, with regard to operation efficiency, pressure loss exerts a greater influence than heat transfer capacity in the heat absorption process, and heat transfer capacity exerts a greater influence than pressure loss in the heat radiation process. - Accordingly, in the air-conditioning apparatus according to
Embodiment 4, in the intermediate heat exchanger 107aa (107ba) that functions as an evaporator, the primary-side refrigerant performs a heat absorption operation, and flows through theheat transfer unit 1071 a (1071b) and theheat transfer unit 1072a (1072b) in parallel so that the overall cross-sectional area of the flow path becomes large. Therefore, pressure loss that tends to exert a great influence in the heat absorption process can be reduced, thereby making it possible to reduce the input to thecompressor 103. - In the intermediate heat exchanger 107aa (107ba) that functions as a radiator, the primary-side refrigerant performs a heat radiation operation, and flows through the
heat transfer unit 1071a (1071b) and theheat transfer unit 1072a (1072b) in series so that the overall cross-sectional area of the flow path becomes small. Thus, flow velocity increases, thereby making it possible to promote heat transfer. Therefore, highly efficient operation is possible in each operation mode. - In the air-conditioning apparatus according to
Embodiment 4, there exists a heat transfer unit (theheat transfer unit 1071b inFIGs. 18 and19 ) in which the flow directions of both the primary-side refrigerant and the secondary-side refrigerant do not change even when the overall cross-sectional area of the flow path in the intermediate heat exchanger changes in accordance with each operation mode. Consequently, it is possible to take measures such as optimization of refrigerant distribution. - In each operation mode, even when the flow direction of the secondary-side refrigerant is switched, the secondary-side refrigerant flows through the indoor heat exchangers 108n only in one direction, and in either case, heat exchange with the indoor air is performed in the same manner, resulting in high heat exchange efficiency.
- Use of the
check valves 132a to 132f and 133a to 133f makes it unnecessary to perform operations other than operations of the four-way valve 106 and each valve, for switching of the overall cross-sectional area of the flow path in each of the intermediate heat exchangers 107aa and 107ba due to switching of operation modes. Consequently, in the vicinity of each of the intermediate heat exchangers 107aa and 107ba, problems such as leakage of refrigerant from valves can be prevented, thereby enabling safe operation. - The configuration of the intermediate heat exchangers 107aa and 107a of the air-conditioning apparatus according to
Embodiment 4 can be also applied to the air-conditioning apparatus according to Embodiment 3. - While the air-conditioning apparatus illustrated in
FIG. 17 is configured so that the intermediate heat exchangers 107aa and 107ba each include two heat transfer units such as theheat transfer unit 1071a (1071b) and theheat transfer unit 1072a (1072b), this should not be construed restrictively. The intermediate heat exchangers 107aa and 107ba may each include three or more heat transfer units. - As an example in this case,
FIG. 20 illustrates a configuration in which the intermediate heat exchangers 107aa and 107a each include three heat transfer units (heat transfer units 1071a to 1073a (1071b to 1073b)). In a case where the number of heat transfer units is an even number, the resulting configuration is the same as the configuration illustrated inFIG. 17 . - That is, letting 2n (n is a natural number not smaller than 1) represent the number of heat transfer units, the number of check valves belonging to the primary-side refrigerant circuit within each of the intermediate heat exchangers 107aa and 107ba (the
check valves 132a to 132f inFIG. 17 ), and the number of check valves belonging to the secondary-side refrigerant circuit (thecheck valves 133a to 133f inFIG. 17 ) are each expressed as (2n+1). In a case where the number of heat transfer units is an odd number, the resulting configuration is the same as the configuration illustrated inFIG. 20 . - That is, letting (2n+1) represent the number of heat transfer units, the number of check valves belonging to the primary-side refrigerant circuit within each of the intermediate heat exchangers 107aa and 107ba (the
check valves FIG. 20 ), and the number of check valves belonging to the secondary-side refrigerant circuit (thecheck valves FIG. 20 ) are each expressed as 2n. - Therefore, the number of check valves to be installed relative to the number of heat transfer units can be reduced in the case where the number of heat transfer units is an odd number.
- In a case where the number of heat transfer units in each of the intermediate heat exchangers 107aa and 107ba is an even number, the number of the above-mentioned heat transfer units in which the flow directions of both the primary-side refrigerant and the secondary-side refrigerant do not change equals 50 % of the total number of heat transfer units.
- In a case where the number of heat transfer units in each of the intermediate heat exchangers 107aa and 107ba is an odd number, provided that the number is three, the number of heat transfer units in which both of the flow directions do not change equals 33.3 % of the total number of heat transfer units and its ratio becomes the lowest.
- That is, in the case where the number of heat transfer units is an odd number, when the number of heat transfer units is larger than three, and as the number of heat transfer units becomes larger, the ratio of the number of heat transfer units in which both of the flow directions do not change to the total number of heat transfer units becomes larger.
- The check valves inside each of the intermediate heat exchangers 107aa and 107ba in the air-conditioning apparatus illustrated in
FIGs. 17 and20 may be valves that can be opened and closed. In this case, for example, although an operation according to each operation mode becomes necessary, equipment cost can be reduced. -
FIG. 21 is a schematic diagram of an air-conditioning apparatus according toEmbodiment 5 of the present invention. - In the configuration of the air-conditioning apparatus according to
Embodiment 5 illustrated inFIG. 21 , thecheck valves 110e to 110h are omitted from the air-conditioning apparatus according to Embodiment 3. - When the
check valves 110e to 110h are eliminated as in the configuration mentioned above, the flow of the secondary-side refrigerant flowing through theintermediate heat exchanger 107b becomes a certain direction. Accordingly, in a case where theintermediate heat exchanger 107b acts an evaporator, the primary-side refrigerant and the secondary-side refrigerant are not in counterflow, resulting in poor efficiency. - However, generally, the effect of counterflow is greater in the case where the
intermediate heat exchanger 107b acts as a condenser than in the case where theintermediate heat exchanger 107b acts as an evaporator, and of the four operation modes, theintermediate heat exchanger 107b acts as an evaporator only in the cooling only operation mode. Therefore, a cost reduction that more than compensates for a decrease in performance can be expected. - Such a configuration in which the
check valves 110e to 110h are omitted can be also applied to the air-conditioning apparatus according to Embodiment 2. -
FIG. 22 illustrates an installation example of an air-conditioning apparatus according toEmbodiment 6 of the present invention. The air-conditioning apparatus illustrated inFIG. 22 will be described by way of an example in which the air-conditioning apparatus is the air-conditioning apparatus according to each of Embodiments 2 to 5, and this air-conditioning apparatus is installed in a building or the like having a plurality of floors. - The outdoor unit A is installed in an outdoor space such as the rooftop of a
building 100 illustrated inFIG. 22 . In addition, in an indoor space that is an air-conditioning space such as a living space inside thebuilding 100, the indoor unit C is installed at a position that allows a cooling operation and a heating operation to be performed for the air in the indoor space. - As illustrated in
FIG. 22 , a plurality of indoor units C (three indoor units C (indoor units C1 to C3) inFIG. 22 ) are installed in the indoor space on each floor of thebuilding 100. The relay unit B is installed in a non-air-conditioned space inside thebuilding 100. The relay unit B is connected to the outdoor unit A and each of the indoor units C by refrigerant pipes. - As illustrated in
FIG. 22 , the relay unit B is installed for each plurality of indoor units C installed on each floor. That is, heat transport between the outdoor unit A and the relay unit B is performed by the primary-side refrigerant, and heat transport between the indoor unit C and the relay unit B is performed by the secondary-side refrigerant. - The air-conditioning apparatus according to
Embodiment 1 may be applied to the air-conditioning apparatus illustrated inFIG. 22 . In this case, the outdoor unit A corresponds to the portion constituting the primary-side refrigerant circuit in the air-conditioning apparatus according to Embodiment 1 (excluding the intermediate heat exchanger 7), and the indoor unit C corresponds to a portion constituting the secondary-side refrigerant circuit in the air-conditioning apparatus which has theindoor heat exchanger 8 and the fan 8a. - The relay unit B corresponds to the
intermediate heat exchanger 7 in the air-conditioning apparatus according toEmbodiment 1, and a portion constituting the secondary-side refrigerant circuit which has the pump 9 and thevalves 10a to 10d. - While the case where the outdoor unit A is installed on the rooftop of the
building 100 as illustrated inFIG. 22 has been described, this should not be construed restrictively. For example, the outdoor unit A may be installed in the basement of thebuilding 100, in the machine room on each floor, or the like. - While three indoor units C are installed on each floor of the
building 100 as illustrated inFIG. 22 , this should not be construed restrictively. For example, one or another number of indoor units C may be installed. - According to the configuration mentioned above, in the air-conditioning apparatus according to
Embodiment 6, the secondary-side refrigerant such as water flows through the refrigerant pipe connected to the indoor unit C installed in an indoor space such as a living space. Therefore, leakage of the primary-side refrigerant to the indoor space can be prevented. - The outdoor unit A and the indoor unit C are installed in places other than an indoor space such as a living space, which allows for easy maintenance of these units.
-
- 3
- = compressor
- 4
- = outdoor heat exchanger
- 4a
- = fan
- 5
- = expansion mechanism
- 6
- = four-way valve
- 7
- = intermediate heat exchanger
- 7a, 7b
- = heat transfer unit
- 8
- = indoor heat exchanger
- 8a
- = fan
- 9
- = pump
- 10a, 10b, 10c, 10d
- = valve
- 11a to 11c
- = check valve
- 12a to 12c
- = check valve
- 20a to 20d
- = branch part
- 3a to 30d
- = branch part
- 31a to 31d
- = branch part
- 100
- = building
- 103
- = compressor
- 104
- = outdoor heat exchanger
- 105a, 105b
- = expansion mechanism
- 106
- = four-way valve
- 107a, 147b, 107aa, 107ba
- = intermediate heat exchanger
- 109a, 109b
- = pump
- 110a to 110h
- = valve
- 111a to 111f
- = valve
- 113a to 113d
- = check valve
- 132a to 132f
- = check valve
- 133a to 133f
- = check valve
- 141
- = flow switching unit
- 142
- = bypass pipe
- 1071a, 1071b
- = heat transfer unit
- 1072a, 1072b
- = heat transfer unit
- 1081 to 1083
- = indoor heat exchanger
- 1121a to 1121d
- = valve
- 1122a to 1122d
- = valve
- 1123a to 1123d
- = valve
- A
- = outdoor unit
- B
- = relay unit
- C1 to C3
- = indoor unit
Claims (18)
- An air-conditioning apparatus comprising:- a primary-side refrigerant circuit in which a compressor, first flow switching means, a heat source-side heat exchanger, second flow switching means, a plurality of intermediate heat exchangers, and an expansion mechanism are connected by refrigerant pipes, and through which a primary-side refrigerant flows; and- a secondary-side refrigerant circuit in which the plurality of the intermediate heat exchangers, third flow switching means, a pump, fourth flow switching means, and a plurality of use-side heat exchangers are connected by refrigerant pipes, and through which a secondary-side refrigerant different from the primary-side refrigerant flows,- wherein the intermediate heat exchangers are adapted to exchange heat between the primary-side refrigerant and the secondary-side refrigerant,- the first flow switching means are adapted to switch a refrigerant flow path so that the primary-side refrigerant discharged from the compressor flows to the intermediate heat exchangers or the heat source-side heat exchanger,- wherein the second flow switching means are adapted to switch flow directions of the primary-side refrigerant flowing into the intermediate heat exchangers,- wherein the third flow switching means are adapted to switch flow directions of the secondary-side refrigerant flowing into the intermediate heat exchangers,- wherein the fourth flow switching means are adapted to allow at least one of the plurality of the use-side heat exchangers to perform, in a selectable manner, one of a cooling operation and a heating operation, by switching a refrigerant flow path to direct any one of flows of the secondary-side refrigerant that has flown through the plurality of the intermediate heat exchangers, and- wherein the second flow switching means and the third flow switching means are each adapted to switch a refrigerant flow path so that the primary-side refrigerant and the secondary-side refrigerant are in counterflow in at least one of the intermediate heat exchangers.
- The air-conditioning apparatus of claim 1,
wherein in a case where both the cooling operation and the heating operation are being performed in the plurality of the use-side heat exchangers as a result of each of the use-side heat exchangers performing the cooling operation or the heating operation, and a cooling load is greater than a heating load, the second flow switching means and the third flow switching means are each adapted to switch a refrigerant flow path so that the primary-side refrigerant and the secondary-side refrigerant are in counterflow in all of the intermediate heat exchangers. - The air-conditioning apparatus of claim 1,
wherein in a case where both the cooling operation and the heating operation are being performed in the use-side heat exchangers as a result of the cooling operation or the heating operation performed by each of the use-side heat exchangers, and a heating load is greater than a cooling load, the second flow switching means and the third flow switching means are each adapted to switch a refrigerant flow path so that the primary-side refrigerant and the secondary-side refrigerant are in counterflow in all of the intermediate heat exchangers. - The air-conditioning apparatus of claim 1,
wherein the second flow switching means and the third flow switching means are each adapted to switch a refrigerant flow path so that the primary-side refrigerant and the secondary-side refrigerant are in counterflow in all of the intermediate heat exchangers. - The air-conditioning apparatus of any one of claims 1 to 4,
wherein each of the intermediate heat exchangers has heat transfer units and fifth flow switching means;
wherein the heat transfer units are adapted to exchange heat so that the primary-side refrigerant absorbs heat from the secondary-side refrigerant in a case where an intermediate heat exchanger having the heat transfer units functions as an evaporator, and exchange heat so that the primary-side refrigerant radiates heat to the secondary-side refrigerant in a case where the intermediate heat exchanger having the heat transfer units functions as a radiator; and
wherein the fifth flow switching means are adapted to switch a refrigerant flow path so that in the intermediate heat exchanger, a cross-sectional area of a flow path of the primary-side refrigerant becomes larger in a case where the intermediate heat exchanger functions as an evaporator than in a case where the intermediate heat exchanger functions as a radiator. - The air-conditioning apparatus of claim 5,
wherein the fifth flow switching means is configured by a check valve; and
wherein the cross-sectional area of the flow path of the primary-side refrigerant is adapted to be switched by the check valve in accordance with respective inflow directions of the primary-side refrigerant and the secondary-side refrigerant that flow into the intermediate heat exchanger. - The air-conditioning apparatus of claim 5 or 6,
wherein each of the intermediate heat exchangers has a plurality of the heat transfer units;
wherein the fifth flow switching means are adapted to switch a refrigerant flow path so that the primary-side refrigerant and the secondary-side refrigerant flow through the heat transfer units in parallel, in a case where the intermediate heat exchanger functions as an evaporator; and wherein the fifth flow switching means are adapted to switch a refrigerant flow path so that the primary-side refrigerant and the secondary-side refrigerant flow through the heat transfer units in series, in a case where the intermediate heat exchanger functions as a radiator. - The air-conditioning apparatus of claim 7,
wherein the intermediate heat exchanger has at least one of the heat transfer units in which respective flows of the primary-side refrigerant and the secondary-side refrigerant flow in a certain direction in both of a case where the intermediate heat exchanger functions as an evaporator and a case where the intermediate heat exchanger functions as a radiator. - An air-conditioning apparatus comprising:- a primary-side refrigerant circuit in which a compressor, first flow switching means, a heat source-side heat exchanger, an expansion mechanism, and an intermediate heat exchanger are connected by refrigerant pipes, and through which a primary-side refrigerant flows; and- a secondary-side refrigerant circuit in which a pump, a use-side heat exchanger, second flow switching means, and the intermediate heat exchanger are connected by refrigerant pipes, and through which a secondary-side refrigerant different from the primary-side refrigerant flows,- wherein the intermediate heat exchanger has heat transfer units and third flow switching means,- wherein the heat transfer units are adapted to perform heat exchange so that the primary-side refrigerant absorbs heat from the secondary-side refrigerant in a cooling operation, and that the primary-side refrigerant radiates heat to the secondary-side refrigerant in a heating operation,- wherein the first flow switching means are adapted to switch a refrigerant flow path so that the primary-side refrigerant discharged from the compressor flows to the heat source-side heat exchanger in the cooling operation, and switch a refrigerant flow path so that the primary-side refrigerant discharged from the compressor flows to the intermediate heat exchanger in the heating operation,- wherein the second flow switching means are adapted to switch a flow direction of the secondary-side refrigerant flowing into the intermediate heat exchanger, and- wherein the third flow switching means are adapted to switch a refrigerant flow path so that in the intermediate heat exchanger, a cross-sectional area of a refrigerant flow path through which the primary-side refrigerant flows becomes larger in the cooling operation than that of in the heating operation.
- The air-conditioning apparatus of claim 9,
wherein the third flow switching means is configured by a check valve; and- wherein the cross-sectional area of the flow path of the primary-side refrigerant are adapted to be switched by the check valve in accordance with respective inflow directions of the primary-side refrigerant and the secondary-side refrigerant that flow into the intermediate heat exchanger. - The air-conditioning apparatus of claim 9 or 10,
wherein the intermediate heat exchanger has a plurality of the heat transfer units;
wherein the third flow switching means are adapted to switch a refrigerant flow path in the cooling operation so that the primary-side refrigerant and the secondary-side refrigerant flow through the heat transfer units in parallel; and
wherein the third flow switching means are adapted to switch a refrigerant flow path in the heating operation so that the primary-side refrigerant and the secondary-side refrigerant flow through the heat transfer units in series. - The air-conditioning apparatus of any one of claims 9 to 11,
wherein the intermediate heat exchanger has at least one of the heat transfer units in which respective flow directions of the primary-side refrigerant and the secondary-side refrigerant do not change in both the cooling operation and the heating operation. - The air-conditioning apparatus of one of claims 9 to 12,
wherein in the heating operation, a target value of an outlet-inlet temperature difference in the intermediate heat exchanger through which the secondary-side refrigerant flows, or an outlet-inlet temperature difference in the use-side heat exchanger is set larger than the target value in the cooling operation. - The air-conditioning apparatus of any one of claims 1 to 8, comprising:- an outdoor unit including the compressor, the first flow switching means, the heat source-side heat exchanger, and the expansion mechanism;- an indoor unit including the use-side heat exchangers; and- a relay unit including the intermediate heat exchangers, the pump, the second flow switching means, the third flow switching means, and the fourth flow switching means,- wherein the indoor unit is installed in an air-conditioned space,- wherein the outdoor unit and the relay unit is installed in a non-air-conditioned space,- wherein the primary-side refrigerant is adapted to flow between the outdoor unit and the relay unit, and- wherein the secondary-side refrigerant is adapted to flow between the indoor unit and the relay unit.
- The air-conditioning apparatus of any one of claims 9 to 13, comprising:- an outdoor unit including the compressor, the first flow switching means, the heat source-side heat exchanger, and the expansion mechanism;- an indoor unit including the use-side heat exchanger; and- a relay unit including the intermediate heat exchanger, the pump, and the second flow switching means,wherein the indoor unit is installed in an air-conditioned space, wherein the outdoor unit and the relay unit is installed in a non-air-conditioned space,
wherein the primary-side refrigerant is adapted to flow between the outdoor unit and the relay unit, and
wherein the secondary-side refrigerant are adapted to flow between the indoor unit and the relay unit. - The air-conditioning apparatus of any one of claims 1 to 15,
wherein the primary-side refrigerant is a zeotropic refrigerant mixture. - The air-conditioning apparatus of any one of claims 1 to 15,
wherein a discharge pressure of the primary-side refrigerant exceeds a critical point. - The air-conditioning apparatus of any one of claims 1 to 17,
wherein the secondary-side refrigerant is brine, water, a liquid mixture of brine and water, or a liquid mixture of water and an additive having an anti-corrosion effect.
Applications Claiming Priority (2)
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PCT/JP2012/000397 WO2012132172A1 (en) | 2011-03-28 | 2012-01-23 | Air conditioning apparatus |
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EP (1) | EP2693134B1 (en) |
JP (1) | JP5709978B2 (en) |
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EP4089344A4 (en) * | 2020-01-09 | 2022-12-28 | Mitsubishi Electric Corporation | Air conditioning apparatus |
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JPWO2015111175A1 (en) * | 2014-01-23 | 2017-03-23 | 三菱電機株式会社 | Heat pump equipment |
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JP6529663B2 (en) * | 2016-04-21 | 2019-06-12 | 三菱電機株式会社 | Exhaust heat recovery type air conditioner |
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CN103443556B (en) | 2016-06-15 |
WO2012132172A1 (en) | 2012-10-04 |
US20140007607A1 (en) | 2014-01-09 |
JPWO2012132172A1 (en) | 2014-07-24 |
US9441862B2 (en) | 2016-09-13 |
EP2693134B1 (en) | 2018-08-29 |
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JP5709978B2 (en) | 2015-04-30 |
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